Effects of prepartum dietary protein level and feed intake on postpartum lactation performance and feeding behavior of multiparous Holstein dairy cows

An experiment was conducted to determine the effects of low and high metabolizable protein (MP) diets when fed for ad libitum and controlled intake during the prepartum period on postpartum lactation performance and feeding behavior of dairy cows. Thirty-six multiparous Holstein cows were blocked by parity, expected calving date, and previous lactation milk yield at −21 d relative to expected calving and were randomly assigned to 1 of 4 close-up period dietary treatments providing low MP (LMP) or high MP (HMP) diets with controlled intake (CNI) or ad libitum intake (ALI). The concentrations of MP were 65 and 90 g/kg dry matter for LMP and HMP diets, respectively, whereas intake was controlled to supply 100 and 160% of the NRC (2001) energy requirements for CNI and ALI groups, respectively. The concentration of net energy for lactation (NE_L) in the treatment diets was 1.50 Mcal/kg. All cows were fed a similar lactation diet after calving (1.50 Mcal/kg of NE_L and 83.3 g/kg of MP). The HMP diet increased dry matter intake during the first 3 wk and tended to increase dry matter intake over the 9 wk of lactation. Meal size and eating rate increased in the ALI cows during the prepartum period. Meal frequency increased with the HMP diet during the postpartum period. Milk yield increased by 15.2% with the HMP diet over the 9 wk of lactation. The HMP diet increased energy-corrected milk (ECM) yield in CNI versus ALI cows, whereas the LMP diet increased ECM yield in ALI versus CNI cows over the 9 wk of lactation. The increase in ECM yield of LMP-ALI versus LMP-CNI cows was supported by greater body condition loss and serum β-hydroxybutyrate over the 9 wk of lactation. Taken together, these data indicate that prepartum controlled intake of a high protein diet can provide the benefits of both strategies.     

Meta-analysis of the effects of prepartum dietary protein on performance of dairy cows

The objectives were to review the published literature and use meta-analytic methods to determine the effects of dietary protein fed prepartum on productive performance of dairy cows. The hypothesis was that responses to dietary protein prepartum would differ between nulliparous and parous cows, and performance would be maximized at a greater protein supply in nulliparous than in parous cows. The literature was systematically reviewed, searching randomized experiments in which the prepartum dietary content or degradability of protein was manipulated. Twenty-seven experiments including 125 treatment means and 1,801 cows were included in the meta-analysis. Of those, 8 experiments with 27 treatment means reported responses for 510 nulliparous cows. Data collected included the ingredient composition and chemical analyses of prepartum diets, parity group, and means and respective measures of variance for productive responses. Mixed model meta-analysis was conducted and statistical models investigated the effects of dietary crude protein (CP) or supply of metabolizable protein (MP) prepartum on performance. Supply of MP was predicted using the National Research Council Nutrient Requirements of Dairy Cattle (2001) model. The mean ± standard deviation and median (range) concentrations of dietary CP fed to cows prepartum were 14.4 ± 2.2 and 14.4% (8.9 to 20.9%), resulting in mean and median (range) intakes of CP prepartum of 1,720 ± 432 and 1,734 g/d (745 to 2,482 g/d). Predicted prepartum supply of MP averaged 822 ± 157 in nulliparous cows, ranging from 517 to 1,094 g/d, and 1,146 ± 316 in parous cows, ranging from 463 to 1,733 g/d. Increasing prepartum CP content or predicted supply of MP improved postpartum dry matter intake in nulliparous cows, but increasing prepartum CP content reduced prepartum dry matter intake in parous cows. Yields of milk and fat-corrected milk increased with increasing prepartum supply of MP in nulliparous but not in parous cows. Yields of fat and protein increased in nulliparous cows with increased CP content or supply of MP. Alternatively, in parous cows, yield of milk fat was not influenced by supply of MP but responded quadratically to dietary CP content and was maximized at approximately 14% CP. Dietary CP had no effect on protein yield in parous cows, but increasing the supply of MP improved protein yield only in cows from experiments with >36 kg/d of milk production, whereas MP supply had no effect on protein yield of parous cows from experiments with <28 kg/d of milk production. Performance of dairy cows was responsive to prepartum supply of MP and nulliparous benefited from diets with increased MP intake. Based on current results, production responses for nulliparous cows increased linearly up to the maximum MP intake of 1,100 g/d observed in the study, whereas for parous cows, only yield of milk protein in cows producing more than 36 kg of milk/d was influenced by supplying more than 800 g/d of MP.     

Effects of prepartum 2,4-thiazolidinedione on metabolism and performance in transition dairy cows

Thiazolidinediones (TZD) are potent synthetic ligands for peroxisome proliferator-activated receptor-γ that have been shown previously to reduce plasma nonesterified fatty acids and increase peripartal dry matter intake (DMI) in dairy cows. Data from Holstein cows (n = 36) entering their second or greater lactation were used to determine whether late prepartum administration of TZD would affect periparturient metabolism, milk production, and ovarian activity. Cows were administered 0, 2.0, or 4.0 mg of TZD/kg of BW by intrajugular infusion once daily from 21 d before expected parturition until parturition. Plasma samples were collected daily from 22 d before expected parturition through 21 d postpartum and twice weekly from wk 4 through 9 postpartum. In response to increasing TZD dosage, plasma nonesterified fatty acid concentrations decreased linearly during the postpartum period (d 0 to +21: 348, 331, 268 ± 31 μEq/L, respectively). Plasma concentrations of glucose were highest in cows administered 4.0 mg of TZD/kg of BW during the peripartum and postpartum periods (d −7 to +7: 57.9, 57.8, 61.1 ± 0.8 mg/dL and d 0 to +21: 51.6, 49.3, 54.7 ± 1.1 mg/dL, respectively). Plasma concentrations of β-hydroxybutyrate were increased during the peripartum period by TZD administration (9.6, 9.9, 10.2 ± 0.3 mg/dL) but were not affected during the postpartum period. Plasma insulin was not affected by treatment during any time period. Postpartum liver triglyceride content was decreased linearly (11.0, 10.4, 4.2 ± 1.6%) and glycogen content was increased linearly (2.16, 2.38, 2.79 ± 0.19%) by prepartum TZD administration. Prepartum TZD administration linearly increased DMI during the peripartum period (d −7 to +7: 16.1, 17.2, 17.3 ± 0.5 kg/d). Cows administered TZD prepartum maintained higher postpartum body condition scores than control cows (wk 1 through 9: 2.77, 2.89, 3.02 ± 0.05). There was no effect of prepartum TZD on milk yield; however, yields of 3.5% fat-corrected milk (52.2, 54.6, 48.0 ± 1.6 kg/d) and most other milk components were decreased in cows that received 4.0 mg of TZD/kg of BW prepartum. Prepartum TZD administration linearly decreased the number of days to first ovulation (29.3, 28.3, 19.0 ± 3.6 d). These results suggest that prepartum administration of TZD improves metabolic health and DMI of periparturient dairy cows and may decrease reliance on body fat reserves during early lactation.     

Effects of prepartum diets varying in dietary energy density and monensin on early-lactation performance in dairy cows

Our objectives were to evaluate the effects of prepartum monensin supplementation and dry-period nutritional strategy on the postpartum productive performance of cows fed monensin during lactation. A total of 102 Holstein cows were enrolled in the experiment (32 primiparous and 70 multiparous). The study was a completely randomized design, with randomization restricted to balance for parity, body condition score, and expected calving date. A 2 × 2 factorial arrangement of prepartum treatments was used; the variables of interest were prepartum feeding strategy [controlled-energy diet throughout the dry period (CE) vs. controlled-energy diet from dry-off to 22 d before expected parturition, followed by a moderate-energy close-up diet from d 21 before expected parturition through parturition (CU)] and prepartum monensin supplementation [0 g/t (control, CON) or 24.2 g/t (MON); Rumensin; Elanco Animal Health, Greenfield, IN]. Lactation diets before and after the dry period contained monensin at 15.4 g/t. During the close-up period, cows fed CU had greater DM and NE_L intakes than cows fed CE. Calf BW at birth tended to be greater for cows fed CU than for those fed CE but was not affected by MON supplementation. Diet did not affect calving difficulty score, but cows supplemented with MON had an increased calving difficulty score. We found a tendency for a MON × parity interaction for colostral IgG concentration, such that multiparous MON cows tended to have lower IgG concentration than CON cows, but colostral IgG concentration for primiparous MON and CON cows did not differ. Postpartum milk yield did not differ between diets but tended to be greater for cows supplemented with MON. Milk fat and lactose content were greater for cows fed CU than for those fed CE, and lactose content and yield were increased for cows supplemented with MON. Solids-corrected and fat-corrected milk yields were increased by MON supplementation, but were not affected by diet. Overall means for postpartum DMI did not differ by diet or MON supplementation. The CU diet decreased the concentration of nonesterified fatty acids during the close-up period but increased it postpartum. Neither diet nor monensin affected β-hydroxybutyrate or liver composition. Overall, postpartum productive performance differed little between prepartum dietary strategies, but cows fed MON had greater energy-corrected milk production. In herds fed monensin during lactation, monensin should also be fed during the dry period.     

Abomasal protein infusion in postpartum transition dairy cows: Effect on performance and mammary metabolism

The effect of increasing the postpartum metabolizable protein (MP) supply on performance and mammary metabolism was studied using 8 Holstein cows in a complete randomized design. At parturition, cows were assigned to abomasal infusion of water (CTRL) or casein (CAS). Arterial and epigastric venous blood samples were taken 14 d before expected parturition and at 4, 15, and 29 d in milk (DIM). To compensate previously estimated deficiency of essential AA and to avoid oversupply, casein protein infusion was graduated with 696 ± 1, 490 ± 9, and 212 ± 10 g/d at 4, 15 and 29 DIM, respectively. Dry matter intake was unaffected by CAS. Compared with CTRL, MP supply was greater at 4 DIM with CAS but did not differ by 29 DIM. Milk yield was greater with CAS (+7.2 ± 1.3 kg/d from 1 to 29 DIM). Milk protein yield was greater with CAS at 4 DIM and averaged 1,664 ± 39 g/d compared with 1,212 ± 86 g/d for CTRL, but did not differ at 29 DIM (1,383 ± 48 g/d). The ratio of MP total supply to requirement was numerically greater at 4 DIM for CAS compared with CTRL, indicating less postpartum protein deficiency. In contrast, a greater net energy deficiency tended to be induced with CAS, but the greater milk yield allowed a large part of mobilized fat to be secreted in milk. Arterial concentration of total essential AA increased sharply after parturition for CAS compared with slight decreases for CTRL. The patterns of arterial concentrations combined with arterial-mammary venous concentration differences indicated that Lys, Leu, and Tyr were the first-limiting AA at 4 DIM with CTRL. Mammary plasma flow was unaffected by treatment, indicating similar perfusion of mammary tissue. The greater milk yield with CAS was associated with greater mammary uptake of individual essential AA, tendencies to greater uptake of glucose, lactate, and β-hydroxybutyrate, whereas uptakes of volatile fatty acids were unaffected. Despite similar MP supply by 29 DIM, milk and lactose yields were greater with CAS indicating a persistent response to increased postpartum MP supply. In conclusion, the postpartum MP deficiency can have a substantial negative effect in dairy cows as the major outcome of increasing the postpartum MP supply was increased milk, milk protein, and lactose yield, as well as an enhanced MP balance. Potential positive effects for other body functions than milk synthesis are discussed. Future investigations are needed to delineate how to transfer the effect into practical feeding strategies.     

Effects of prepartum dietary cation-anion difference on aspects of peripartum mineral and energy metabolism and performance of multiparous Holstein cows

The objectives of this study were to determine the effect of decreasing dietary cation-anion difference [DCAD; (Na⁺ + K⁺) ? (Cl^? + S^2?)] of the prepartum diet on aspects of mineral metabolism, energy metabolism, and performance of peripartum dairy cows. Multiparous Holstein cows (n = 89) were enrolled between 38 and 31 d before expected parturition and randomized to treatments in a completely randomized design (restricted to balance for previous 305-d mature equivalent milk production, parity, and body condition score) at 24 d before expected parturition. Treatments consisted of a low-K ration without anion supplementation [CON; n = 30, DCAD = +18.3 mEq/100 g of dry matter (DM)]; partial anion supplementation to a low-K ration (MED; n = 30, DCAD = +5.9 mEq/100 g of DM); and anion supplementation to a low-K ration to reach a targeted average urine pH between 5.5 and 6.0 (LOW; n = 29, DCAD = ?7.4 mEq/100 g of DM). Cows were fed a common postpartum diet and data collected through 63 d in milk. Urine pH (CON = 8.22, MED = 7.89, and LOW = 5.96) was affected quadratically by decreasing prepartum DCAD. A linear relationship between urine pH and urine Ca:creatinine ratio was observed (r = ?0.81). Plasma Ca concentrations in the postpartum period (d 0 to 14; CON = 2.16, MED = 2.19, and LOW = 2.27 mmol/L) were increased linearly with decreasing prepartum DCAD. A treatment by parity (second vs. third and greater) interaction for postpartum plasma Ca concentration suggested that older cows had the greatest response to the low DCAD diet and older cows fed LOW had decreased prevalence of hypocalcemia after calving. A quadratic effect of decreasing DCAD on prepartum DMI was observed (CON = 13.6, MED = 14.0, and LOW = 13.2 kg/d). Milk production in the first 3 wk postpartum was increased linearly with decreasing DCAD (CON = 40.8, MED = 42.4, and LOW = 43.9 kg/d) and DMI in this period also tended to linearly increase (CON = 20.2, MED = 20.9, and LOW = 21.3 kg/d). Overall, effects on intake and milk yield analyzed over wk 1 to 9 postpartum were not significant. This study demonstrates that feeding lower DCAD diets prepartum improves plasma Ca status in the immediate postpartum period and results in increased DMI and milk production in the 3 wk after parturition. Compared with no anion supplementation or lower levels of anion supplementation, greater improvements were observed with the lower DCAD feeding strategy, in which an average urine pH of 5.5 to 6.0 was targeted.     

Prepartum dietary energy intake affects metabolism and health during the periparturient period in primiparous and multiparous Holstein cows

An experiment was conducted to determine the effect of prepartum plane of energy intake on metabolic profiles related to lipid metabolism and health in blood and liver. Primiparous (n = 24) and multiparous (n = 23) Holsteins were randomly assigned by expected date of parturition to 1 of 3 prepartum energy intakes. A high energy diet [1.62 Mcal of net energy for lactation (NE_L)/kg; 15% crude protein] was fed for either ad libitum intake or restricted intake to supply 150% (OVR) or 80% (RES) of energy requirements for dry cows in late gestation. To limit energy intake to 100% of National Research Council requirements at ad libitum intake, chopped wheat straw was included as 31.8% of dry matter for a control diet (CON; 1.21 Mcal of NE_L/kg of dry matter; 14.2% crude protein). Regardless of parity group, OVR cows had greater concentrations of glucose, insulin, and leptin in blood prepartum compared with either CON or RES cows; however, dietary effects did not carry over to the postpartum period. Prepartum nonesterified fatty acids (NEFA) were lower in OVR cows compared with either CON or RES cows. Postpartum, however, OVR cows had evidence of greater mobilization of triacylglycerol (TAG) from adipose tissue as NEFA were higher than in CON or RES cows, especially within the first 10 d postpartum. Prepartum β-hydroxybutyrate (BHBA) was not affected by diet before parturition; however, within the first 10 d postpartum, OVR cows had greater BHBA than CON or RES cows. Prepartum diet did not affect liver composition prepartum; however, OVR cows had greater total lipid and TAG concentrations and lower glycogen postpartum than CON or RES cows. Frequency of ketosis and displaced abomasum was greater for OVR cows compared with CON or RES cows postpartum. Controlling or restricting prepartum energy intake yielded metabolic results that were strikingly similar both prepartum and postpartum, independent of parity group. The use of a bulky diet controlled prepartum energy intake in multiparous and primiparous cows, improved metabolic status postpartum, and reduced the incidence of health problems. When metabolic profiles are considered collectively, cows overfed energy prepartum exhibited an “overnutrition syndrome” with characteristics of clinical symptoms displayed by diabetic or obese nonruminant subjects. This syndrome likely contributed to metabolic dysfunction postpartum.     

Effects of prepartum metabolizable protein supply and management strategy on lactational performance and blood biomarkers in dairy cows during early lactation

Our objective was to investigate the effects of prepartum metabolizable protein (MP) supply and management strategy on milk production and blood biomarkers in early lactation dairy cows. Ninety-six multigravida Holstein cows were used in a randomized complete block design study, blocked by calving date, and then assigned randomly to 1 of 3 treatments within block. Cows on the first treatment were fed a far-off lower MP diet [MP = 83 g/kg of dry matter (DM)] between ?55 and ?22 d before expected calving and then a close-up lower MP diet (MP = 83 g/kg of DM) until parturition (LPLP). Cows on the second treatment were fed the far-off lower MP diet between ?55 to ?22 d before expected parturition and then a prepartum higher MP diet (MP = 107 g/kg of DM) until calving (LPHP). Cows on the third treatment had a shortened 43-d dry period and were fed the prepartum higher MP diet from dry-off to parturition (SDHP). After calving, cows received the same fresh diet from d 0 to 14 and the same high diet from d 15 to 84. Data were analyzed separately for wk ?6 to ?1 and wk 1 to 12, relative to parturition. Dry matter intake from wk ?6 to ?1 was not different between LPHP and LPLP and increased for SDHP compared with LPLP. In contrast, dry matter intake for wk 1 to 12 postpartum did not change for LPHP versus LPLP or for SDHP versus LPLP. Compared with LPLP cows, LPHP cows had lower energy-corrected milk yield and tended to have decreased milk fat yield during wk 1 to 12 of lactation. Conversely, yields of energy-corrected milk and milk fat and protein were similar for SDHP compared with LPLP. Plasma urea N during wk ?3 to ?1 increased for LPHP versus LPLP and for SDHP versus LPLP; however, no differences in plasma urea N were observed postpartum. Elevated prepartum MP supply did not modify circulating total fatty acids, β-hydroxybutyrate, total protein, albumin, or aspartate aminotransferase during the prepartum and postpartum periods. Increased MP supply prepartum combined with a shorter dry period (SDHP vs. LPLP) tended to increase whole-blood β-hydroxybutyrate postpartum; however, other blood metabolites were not affected. Taken together, under the conditions of this study, elevated MP supply in close-up diets reduced milk production without affecting blood metabolites in multiparous dairy cows during early lactation. A combination of a shorter dry period and increased prepartum MP supply (i.e., SDHP vs. LPLP) improved prepartum dry matter intake without modifying energy-corrected milk yield and blood biomarkers in early lactation cows.     

Effects of level of dietary cation-anion difference and duration of prepartum feeding on performance and metabolism of dairy cows

The objectives were to evaluate the effects of feeding diets with 2 levels of negative dietary cation-anion differences (DCAD) during the last 42 or 21 d of gestation on performance and metabolism in dairy cows. The hypothesis was that extending feeding from 21 to 42 d and reducing the DCAD from ?70 to ?180 mEq/kg of dry matter (DM) would not be detrimental to performance. Holstein cows at 230 d of gestation were blocked by parity prepartum (48 entering their second lactation and 66 entering their third or greater lactation) and 305-d milk yield, and randomly assigned to 1 of 4 treatments arranged as a 2 × 2 factorial. The 2 levels of DCAD, ?70 or ?180 mEq/kg of DM, and 2 feeding durations, the last 21 d (short) or the last 42 d (long) prepartum resulted in 4 treatments, short ?70 (n = 29), short ?180 (n = 29), long ?70 (n = 28) and long ?180 (n = 28). Cows in the short treatments were fed a diet with DCAD of +110 mEq/kg of DM from ?42 to ?22 d relative to calving. After calving, cows were fed the same diet and production and disease incidence were evaluated for 42 d in milk, whereas reproduction and survival was evaluated for 305 d in milk. Blood was sampled pre- and postpartum for quantification of metabolites and minerals. Reducing the DCAD linearly decreased prepartum DM intake between ?42 and ?22 d relative to calving (+110 mEq/kg of DM = 11.5 vs. ?70 mEq/kg of DM = 10.7 vs. ?180 mEq/kg of DM = 10.2 ± 0.4), and a more acidogenic diet in the last 21 d of the dry period reduced intake by 1.1 kg/d (?70 mEq/kg of DM = 10.8 vs. ?180 mEq/kg of DM = 9.7 ± 0.5 kg/d). Cows fed the ?180 mEq/kg of DM diet had increased concentrations of ionized Ca in blood on the day of calving (?70 mEq/kg of DM = 1.063 vs. ?180 mEq/kg of DM = 1.128 ± 0.020 mM). Extending the duration of feeding the diets with negative DCAD from 21 to 42 d reduced gestation length by 2 d (short = 277.2 vs. long = 275.3 d), milk yield by 2.5 kg/d (short = 40.4 vs. long = 37.9 ± 1.0 kg/d) and tended to increase days open because of reduced pregnancy per artificial insemination (short = 35.0 vs. long = 22.6%). Results suggest that increasing the duration of feeding diets with negative DCAD from 21 to 42 d prepartum might influence milk yield and reproduction of cows in the subsequent lactation, although yields of 3.5% fat- and energy-corrected milk did not differ with treatments. Reducing the DCAD from ?70 to ?180 mEq/kg of DM induced a more severe metabolic acidosis, increased ionized Ca concentrations prepartum and on the day of calving, and decreased colostrum yield in the first milking, but had no effects on performance in the subsequent lactation. Collectively, these data suggest that extending the feeding of an acidogenic diet beyond 21 d is unnecessary and might be detrimental to dairy cows, and a reduction in the DCAD from ?70 to ?180 mEq/kg of DM is not needed.     

Production,metabolism, and follicular dynamics in multiparous dairy cows fed diets providing different amounts of metabolizable protein prepartum and postpartum

Our objectives were (1) to determine whether increasing metabolizable protein (MP) supply above requirements in late-gestation cows would benefit health, milk production, and reproduction; (2) to determine whether an increased supply of MP postpartum affects production; and (3) to determine whether supply of MP prepartum interacts with MP supply postpartum. Pregnant nonlactating cows (n = 60) blocked by expected parturition date were assigned to 1 of 3 prepartum diets from 21 d prepartum to parturition: 12% crude protein (CP) soybean meal (SBM) supplement (LSB); 15% CP SBM supplement (HSB); and 15% CP SBM plus animal-marine protein supplement (HMP). Diets were formulated to supply an estimated 924, 988, and 1,111 g/d of MP, respectively, at 11.5 kg of dry matter intake (DMI). After parturition, cows received diets containing 18% CP, either from SBM (SB) or SBM plus animal-marine protein (AMP) supplements, that provided 2,056 (SB) or 2,293 g/d (AMP) of MP at 21 kg of DMI; thus, treatments were in a 3 × 2 factorial arrangement. Milk production and DMI were recorded for 63 d postpartum. Prepartum DMI was lower at wk ?3 for cows fed LSB compared with those fed HSB or HMP. Postpartum DMI did not differ significantly between cows fed SB and those fed AMP (20.8 vs. 19.6 kg/d). Milk production did not differ due to prepartum diets or postpartum diets. Milk fat and protein percentages were not affected by prepartum or postpartum diets. Cows fed AMP postpartum tended to produce more milk fat, but 4% fat-corrected milk (FCM) did not differ from SB-supplemented cows (33.6 kg/d vs. 32.2 kg/d). Gross feed efficiency (FCM/DMI) was greater for cows fed AMP postpartum (1.82 vs. 1.68). Prepartum concentrations of urea N in plasma were lower for LSB than for HSB and HMP, and HSB was greater than HMP. Postpartum concentrations of nonesterified fatty acids and β-hydroxybutyrate were greater for cows fed AMP postpartum than for those fed SB. Postpartum urea N was higher for SB than for AMP (14.4 vs. 12.5 mg/dL). Concentration of total protein in plasma was greater postpartum for cows fed HSB or HMP prepartum than for those fed LSB, and was greater postpartum for cows fed AMP than for those fed SB. Hepatic concentrations of total lipids and triglyceride did not differ among treatments. Hepatic glycogen was greater postpartum for cows fed SB postpartum. Feeding HSB or HMP increased the number of follicles 6 to 9 mm in diameter compared with LSB. The size of the largest follicle was increased by HMP compared with HSB. In conclusion, increasing the amount of MP fed to cows during the last 21 d prepartum did not affect milk production or BCS but increased plasma total protein concentration. Follicular dynamics were improved by increasing the amount of MP prepartum. Feeding HMP prepartum improved follicular dynamics prepartum and increased milk fat yield in wk 1. Feeding AMP postpartum increased efficiency of FCM production and plasma total protein. We found few interactions between prepartum and postpartum MP supply.     

Effect of protein level in prepartum diets on metabolism and performance of dairy cows

Multigravid Holstein cows (n = 75) were used in a randomized block design to evaluate the effect of prepartum diets formulated to supply surplus energy and incremental concentrations of protein on the nutritional status of dairy cows at parturition. Cows were blocked according to expected calving date and assigned to one of five diets: 9.7, 11.7, 13.7, 14.7, and 16.2% crude protein (CP). Dietary treatments were initiated 28 d before expected calving date and fed until parturition. A common diet was fed postpartum. Dry matter intake and milk yield were recorded daily through 90 d postpartum. Increasing the protein concentration from 9.7 to 14.7% of dry matter during the last 28 d of gestation improved responses of cows during lactation. Increasing dietary protein up to 14.7% also increased milk yield response to recombinant bovine somatotropin (rbST) during the ninth week of lactation and yields of 305-d 2x mature equivalent milk, milk protein, and milk fat. Plasma aspartate aminotransferase tended to be highest in cows fed 13.7 and 14.7% CP prepartum, but decreased linearly postpartum in response to dietary protein levels. There were no treatment differences for plasma insulin-like growth factor-1 (IGF-1) at d 60 postpartum (before rbST provision), but IGF-1 on d 90 (after rbST provision) was higher in plasma of cows fed 14.7% CP than the other diets except 13.7% CP. Close-up diets containing 13.7% CP and surplus energy produced the most beneficial outcomes during the subsequent lactation.     

Alternatives to linear analysis of energy balance data from lactating dairy cows

The current energy requirements system used in the United Kingdom for lactating dairy cows utilizes key parameters such as metabolizable energy intake (MEI) at maintenance (MEm), the efficiency of utilization of MEI for 1) maintenance, 2) milk production (kl), 3) growth (kg), and the efficiency of utilization of body stores for milk production (kt). Traditionally, these have been determined using linear regression methods to analyze energy balance data from calorimetry experiments. Many studies have highlighted a number of concerns over current energy feeding systems particularly in relation to these key parameters, and the linear models used for analyzing. Therefore, a database containing 652 dairy cow observations was assembled from calorimetry studies in the United Kingdom. Five functions for analyzing energy balance data were considered: straight line, two diminishing returns functions, (the Mitscherlich and the rectangular hyperbola), and two sigmoidal functions (the logistic and the Gompertz). Meta-analysis of the data was conducted to estimate kg and kt. Values of 0.83 to 0.86 and 0.66 to 0.69 were obtained for kg and kt using all the functions (with standard errors of 0.028 and 0.027), respectively, which were considerably different from previous reports of 0.60 to 0.75 for kg and 0.82 to 0.84 for kt. Using the estimated values of kg and kt, the data were corrected to allow for body tissue changes. Based on the definition of kl as the derivative of the ratio of milk energy derived from MEI to MEI directed towards milk production, MEm and kl were determined. Meta-analysis of the pooled data showed that the average kl ranged from 0.50 to 0.58 and MEm ranged between 0.34 and 0.64 MJ/kg of BW0.75 per day. Although the constrained Mitscherlich fitted the data as good as the straight line, more observations at high energy intakes (above 2.4 MJ/kg of BW0.75 per day) are required to determine conclusively whether milk energy is related to MEI linearly or not.     

Effects of day relative to parturition and dietary crude protein on rumen fermentation in prepartum transition cows

Twelve Holstein cows and eight heifers were used in a randomized block design to examine changes in rumen fermentation and blood metabolites as animals fed diets containing 9.1 (low protein, LP) or 11.2% crude protein (moderate protein, MP) approached parturition. Animals were blocked by expected calving date and parity. Diets were isocaloric (1.58 Mcal/kg of dry matter), and the difference in dietary crude protein was achieved by the addition of urea. Diets were fed as total mixed rations for ad libitum intake. Dry matter intake decreased from 12.2 kg/d on d -21 to 9.1 kg/d on d -1 relative to parturition and was unaffected by dietary crude protein or parity. Rumen ammonia concentrations were higher for animals fed the MP diet compared with those fed the LP diet (1.8 vs. 3.7 mM). In situ neutral detergent fiber disappearance was not affected by dietary crude protein after 8 h of incubation, but it did decrease from 25.8% on d -21 to 23.3% on d -1. After 16, 24, and 48 h of incubation, neutral detergent fiber disappearance was greater for animals consuming MP than for animals consuming LP (30.6 vs. 34.4%, 37.0 vs. 44.1%, and 57.9 vs. 65.1%, respectively). There was a parity x treatment interaction after 48 h of incubation. Fiber disappearance was 55.7 or 65.9% for heifers and 60.0 or 64.7% for cows fed LP or MP, respectively. The solids rate of passage was not affected by treatment, parity, or day relative to parturition. Concentrations of plasma nonesterified fatty acid (NEFA) increased from 218 microEq/L on d -21 to 619 microEq/L on d -1. There was an interaction between day relative to parturition and parity on NEFA concentrations. Heifers had plasma NEFA concentrations of 272 and 772 microEq/L on d -21 and -1, respectively. Cows had NEFA concentrations of 164 and 467 microEq/L on d -21 and -1, respectively. Plasma glucose concentrations were affected by parity (65.8 and 58.8 mg/dl for heifers and cows). Plasma urea, NEFA, beta-hydroxybutyrate, and glucose concentrations were not affected by dietary treatment. In conclusion, heifers tended to have higher plasma concentrations of NEFA and glucose, but did not have elevated concentrations of beta-hydroxybutyrate. Rumen fermentation was relatively unaffected by day relative to parturition, but feeding less than 11% crude protein to prefresh transition cows may limit ruminal fiber degradation.     

Effect of dietary level of rumen-degraded protein on production and nitrogen metabolism in lactating dairy cows

Twenty-eight (8 with ruminal cannulas) lactating Holstein cows were assigned to 4 × 4 Latin squares and fed diets with different levels of rumen-degraded protein (RDP) to study the effect of RDP on production and N metabolism. Diets contained [dry matter (DM) basis] 37% corn silage, 13% alfalfa silage, and 50% concentrate. The concentrate contained solvent and lignosulfonate-treated soybean meal and urea, and was adjusted to provide RDP at: 13.2, 12.3, 11.7, and 10.6% of DM in diets A to D, respectively. Intake of DM and yield of milk, fat-corrected milk, and fat were not affected by treatments. Dietary RDP had positive linear effects on milk true protein content and microbial non-ammonia N (NAN) flow at the omasal canal, and a quadratic effect on true protein yield, with maximal protein production at 12.3% RDP. However, dietary RDP had a positive linear effect on total N excretion, with urinary N accounting for most of the increase, and a negative linear effect on environmental N efficiency (kg of milk produced per kg of N excreted). Therefore, a compromise between profitability and environmental quality was achieved at a dietary RDP level of 11.7% of DM. Observed microbial NAN flow and RDP supply were higher and RUP flow was lower than those predicted by the NRC (2001) model. The NRC (2001) model overpredicted production responses to RUP compared with the results in this study. Replacing default NRC degradation rates for protein supplements with rates measured in vivo resulted in similar observed and predicted values, suggesting that in situ degradation rates used by the NRC are slower than apparent rates in this study.     

Effects of anion supplementation to low-potassium prepartum diets on macromineral status and performance of periparturient dairy cows

Data from multiparous Holstein cows (n = 43) were used to determine whether supplementation of anions to low-potassium (K) prepartum diets would improve periparturient energy and macromineral status and affect performance during the postpartum period. Beginning 21 d before expected parturition, cows were fed a control diet (1.29% K; +10 mEq/100 g; n = 21) or a low dietary cation-anion difference (DCAD) diet (1.29% K; −15 mEq/100 g; n = 22) with anions provided through a combination of sulfate from calcium sulfate dihydrate (0.40% S total ration) and chloride (1.17% Cl total ration) from SoyChlor 16-7 (West Central, Ralston, IA). All cows were fed the same postpartum diet from parturition through 63 d postpartum. Feeding anions decreased overall urine pH (8.17 vs. 6.70) during the prepartum period. Overall, peripartum concentrations of plasma Ca, P, and Mg were similar between treatments; however, concentrations of plasma Ca tended to be increased during the first 24 h postcalving in cows fed the low DCAD diet. Overall, concentrations of plasma P tended to be increased by feeding the anionic diet prepartum; this effect was more pronounced during the immediate peripartal period. Anionic supplementation did not affect incidence of clinical (<5 mg/dL) and subclinical (5 to 8 mg/dL) hypocalcemia, clinical hypophosphatemia (<2 mg/dL), or clinical (<1.1 mg/dL) and subclinical (1.1 to 1.8 mg/dL) hypomagnesemia. Nevertheless, subclinical hypophosphatemia (2 to 4 mg/dL) tended to be decreased at 16 h postcalving and was decreased at d 2 postpartum for cows fed the anionic diet prepartum. Anion supplementation decreased prepartum dry matter intake (15.6 vs. 14.4 kg/d), but did not affect postpartum dry matter intake (22.4 vs. 23.0 kg/d), milk yield (46.5 vs. 46.1 kg/d), or content and yield of milk fat and true protein. Plasma concentrations of energy-related metabolites (glucose, nonesterified fatty acids, β-hydroxybutyrate) were similar for both groups during the prepartum and postpartum periods. Glucose rate of appearance was determined by continuous infusion of 6,6-dideuterated glucose in a subset of cows between 6 and 10 d prepartum (control, n = 12; low DCAD, n = 9) and 7 and 10 d postpartum (control, n = 9; low DCAD, n = 8) periods. Glucose rate of appearance was not affected by treatment during the prepartum or postpartum periods. Overall, anion supplementation of low K diets improved P status during the early postpartum period, but did not affect aspects of energy metabolism or periparturient performance.     

Meta-analysis of the effects of prepartum dietary cation-anion difference on performance and health of dairy cows

The objectives were to use meta-analytic methods to determine the effects of changes in dietary cation-anion difference (DCAD) prepartum on productive performance and health of dairy cows. The literature was systematically reviewed, searching randomized experiments with transition cows that manipulated the prepartum DCAD or experiments with acidogenic diets in which dietary Ca, P, or Mg was manipulated. Forty-two experiments, including 134 treatment means and 1,803 cows, were included in the meta-analysis. Of those, 5 experiments with 15 treatment means reported responses for 151 nulliparous cows. Data collected included the mineral composition of prepartum diets, parity group prepartum, breed, days on treatment, and means and respective measure of variance for urine pH, dry matter intake (DMI), body weight, body condition, productive performance, concentrations of minerals and metabolites in blood, and incidence of diseases. Mixed effects meta-analyses were conducted weighting by the inverse of standard error of the means squared to account for the precision of each experiment. Models include the effects of DCAD, parity group prepartum, interaction between DCAD and parity group, and other covariates that showed significance in univariable analysis. Final models were selected based on parsimony and model fit. Reducing the prepartum DCAD reduced intake prepartum but improved intake postpartum in both parity groups. Interactions between DCAD and parity group occurred for yields of milk, fat-corrected milk (FCM), fat, and protein because reducing the DCAD improved those responses in parous cows; however, reducing the DCAD either had no effect on yields of milk and protein or reduced the yield of FCM and fat in nulliparous cows. The resulting equations from the statistical models predicted that reducing the DCAD from +200 to ?100 mEq/kg would increase blood total Ca on the day of calving from 1.86 to 2.04 ± 0.05 mM, DMI postpartum 1.0 kg/d, and milk yield 1.7 kg/d in parous cows. The increased concentrations of blood total Ca at calving and postpartum explained the marked reduction in risk of milk fever in parous cows with a reduction in DCAD. As the DCAD decreased, the risk of retained placenta and metritis also decreased, resulting in fewer disease events per cow in both nulliparous and parous cows. Dietary concentrations of Ca, P, or Mg prepartum had no effect on DMI or yields of milk and FCM; however, increasing dietary Ca within the study range of 0.16 to 1.98% of dry matter tended to increase the risk of milk fever in parous cows regardless of DCAD fed. Collectively, results support the recommendation of prepartum acidogenic diets to result in a negative DCAD to parous cows with improvements in lactation performance and reduced risk of diseases; however, the range of DCAD fed did not allow for detection of an optimum value for postpartum performance. On the other hand, despite improvements in blood concentrations of Ca and reduction in uterine diseases with a reduction in DCAD fed to nulliparous cows, productive performance was either depressed or unaffected and the limited number of experiments did not provide sufficient evidence for a recommended DCAD for this group of cows.     

Effects of monensin on glucose metabolism in transition dairy cows

Eight multiparous periparturient Holstein cows fitted with ruminal cannula were used in a split plot design to evaluate the effects of monensin on plasma glucose metabolism. Diets were top-dressed daily with 0 mg/cow of monensin (control) or 300 mg/cow of monensin (MON) both pre- and postpartum. Plasma glucose kinetic parameters on d ?13 ± 2.0 and 19 ± 1.6 relative to parturition were determined by using stable isotopes. Na-1-¹³C₃-Propionate (labeled propionate) was infused into the rumen to measure glucose synthesis originating from ruminal propionate, and U-¹³C-glucose (labeled glucose) was injected into the jugular vein to determine total glucose kinetics. A sampling period of 480 min following labeled glucose injection was implemented. A compartmental analysis was employed to determine steady state glucose kinetic parameters. To develop a steady state glucose model, the Windows version of SAAM software (WinSAAM) was used. A 4-compartment model was adequate to comprehensively describe plasma glucose metabolism. The main model compartments consisted of propionate and plasma glucose. The time frame of the 480-min sampling period post-tracer glucose infusion allowed accurate quantification of glucose metabolism. The model estimated that glucose input from sources other than ruminal propionate decreased with MON, from 2.26 to 1.09 g/min postpartum. Gluconeogenesis, expressed as the propionate contribution to the plasma glucose pool, increased in cows fed MON (22 vs. 31%), whereas glucose oxidation, expressed as the glucose disposal rate, significantly decreased (1.67 vs. 0.92 g/min). In conclusion, MON may improve the energy status of transition cows by (1) improving the efficiency of propionate to produce glucose and (2) decreasing glucose oxidation in body tissues.     

Liver fat content and lipid metabolism in dairy cows during early lactation and during a mid-lactation feed restriction

During the transition period, the lipid metabolism of dairy cows is markedly affected by energy status. Fatty liver is one of the main health disorders after parturition. The aim of this study was to evaluate the effects of a negative energy balance (NEB) at 2 stages in lactation [NEB at the onset of lactation postpartum (p.p.) and a deliberately induced NEB by feed restriction near 100 d in milk] on liver triglyceride content and parameters of lipid metabolism in plasma and liver based on mRNA abundance of associated genes. Fifty multiparous dairy cows were studied from wk 3 antepartum to approximately wk 17 p.p. in 2 periods. According to their energy balance in period 1 (parturition to wk 12 p.p.), cows were allocated to a control (CON; n = 25) or a restriction group (RES; 70% of energy requirements; n = 25) for 3 wk in mid lactation starting at around 100 d in milk (period 2). Liver triglyceride (TG) content, plasma nonesterified fatty acids (NEFA), and β-hydroxybutyrate were highest in wk 1 p.p. and decreased thereafter. During period 2, feed restriction did not affect liver TG and β-hydroxybutyrate concentration, whereas NEFA concentration was increased in RES cows as compared with CON cows. Hepatic mRNA abundances of tumor necrosis factor α, ATP citrate lyase, mitochondrial glycerol-3-phosphate acyltransferase, and glycerol-3-phosphate dehydrogenase 2 were not altered by lactational and energy status during both experimental periods. The expression of fatty acid synthase was higher in period 2 compared with period 1, but did not differ between RES and CON groups. The mRNA abundance of acetyl-coenzyme A-carboxylase showed a tendency toward higher expression during period 2 compared with period 1. The solute carrier family 27 (fatty acid transporter), member 1 (SLC27A1) was upregulated in wk 1 p.p. and also during feed restriction in RES cows. In conclusion, the present study shows that a NEB has different effects on hepatic lipid metabolism and TG concentration in the liver of dairy cows at early and later lactation. Therefore, the homeorhetic adaptations during the periparturient period trigger excessive responses in metabolism, whereas during the homeostatic control of endocrine and metabolic systems after established lactation, as during the period of feed restriction in the present study, organs are well adapted to metabolic and environmental changes.     

Effects of prepartum dietary cation-anion difference and source of vitamin D in dairy cows: Lactation performance and energy metabolism

The objectives of this experiment were to evaluate the effects of feeding diets with 2 dietary cation-anion difference (DCAD) levels and supplemented with either cholecalciferol (CH) or calcidiol (CA) during late gestation on lactation performance and energetic metabolism in dairy cows. The hypothesis was that combining a prepartum acidogenic diet with calcidiol supplementation would benefit peripartum Ca metabolism and, thus, improve energy metabolism and lactation performance compared with cows fed an alkalogenic diet or cholecalciferol. Holstein cows at 252 d of gestation were blocked by parity (28 nulliparous and 51 parous cows) and milk yield within parous cows, and randomly assigned to 1 of 4 treatments arranged as a 2 × 2 factorial, with 2 levels of DCAD (positive, +130, and negative, ?130 mEq/kg) and 2 sources of vitamin D, CH or CA, fed at 3 mg per 11 kg of diet dry matter (DM). The resulting treatment combinations were positive DCAD with CH (PCH), positive DCAD with CA (PCA), negative DCAD with CH (NCH), or negative DCAD with CA (NCA), which were fed for the last 21 d of gestation. After calving, cows were fed the same lactation diet. Body weight and body condition were evaluated prepartum and for the first 49 d postpartum. Blood was sampled thrice weekly prepartum, and on d 0, 1, 2, 3, and every 3 d thereafter until 30 d postpartum for quantification of hormones and metabolites. Lactation performance was evaluated for the first 49 d postpartum. Feeding a diet with negative DCAD reduced DM intake in parous cows by 2.1 kg/d, but no effect was observed in nulliparous cows. The negative DCAD reduced concentrations of glucose (positive = 4.05 vs. negative = 3.95 mM), insulin (positive = 0.57 vs. negative = 0.45 ng/mL), and insulin-like growth factor-1 (positive = 110 vs. negative = 95 ng/mL) prepartum. Treatments did not affect DM intake postpartum, but CA-supplemented cows tended to produce more colostrum (PCH = 5.86, PCA = 7.68 NCH = 6.21, NCA = 7.96 ± 1.06 kg) and produced more fat-corrected milk (PCH = 37.0, PCA = 40.1 NCH = 37.5, NCA = 41.9 ± 1.8 kg) and milk components compared with CH-supplemented cows. Feeding the negative DCAD numerically increased yield of fat-corrected milk by 1.0 kg/d in both nulliparous and 1.4 kg/d in parous cows. Minor differences were observed in postpartum concentrations of hormones and metabolites linked to energy metabolism among treatments. Results from this experiment indicate that replacing CH with CA supplemented at 3 mg/d during the prepartum period improved postpartum lactation performance in dairy cows.     

Effect of abomasal glucose infusion on splanchnic and whole-body glucose metabolism in periparturient dairy cows

Six periparturient Holstein cows fitted with ruminal cannulas and permanent indwelling catheters in the hepatic portal vein, hepatic vein, mesenteric vein, and an artery were used to study the effects of abomasal glucose infusion on splanchnic and whole-body glucose metabolism. The experimental design was a split plot, with cow as the whole plot, treatment as the whole-plot factor, and days in milk (DIM) as the subplot factor. Cows were assigned to 1 of 2 treatments: the control (no infusion) or infusion (1,500 g/d of glucose infused into the abomasum from the day of calving). Cows were sampled at 12 d prepartum and at 4, 15, and 29 DIM. To study portal-drained visceral uptake of arterial glucose, [U-¹³C]glucose was continuously infused into the jugular vein on sampling days. Postpartum, voluntary dry matter intake and milk yield increased at a lower rate with the infusion compared with the control. The net portal flux of glucose increased with the infusion compared with the control, and 67 ± 5% of the infused glucose was recovered as increased portal flux of glucose. The net hepatic flux of glucose was lower with the infusion compared with the control; however, the net hepatic flux of glucose per kilogram of dry matter intake was not affected by treatment. The arterial concentrations of glucose and insulin decreased and concentrations of nonesterified fatty acids increased from prepartum to 4 DIM with the control, but these effects were not observed with the infusion. The arterial concentration of β-hydroxybutyrate decreased more from prepartum to 4 DIM with the infusion, compared with the control. Uptake of arterial [U-¹³C]glucose in the portal-drained viscera was affected neither by the infusion nor by the DIM and averaged 2.5 ± 0.2%. The whole-body glucose supply changed to be less dependent on the recycling of lactate (Cori cycle) with the infusion. It was concluded that small intestinal glucose absorption is an efficient source of glucose to the peripheral tissues of dairy cows in very early lactation. At least 67% of the available glucose was recovered in the portal vein without affecting hepatic gluconeogenesis. Infused cows produced less milk and had a lower feed intake, indicating that an improved glucogenic status in very early lactation impaired metabolic adaptations to lactation.