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.     

Effects of plane of nutrition and feed deprivation on insulin responses in dairy cattle during late gestation

Nonlactating Holstein cows (n=12) in late pregnancy were used to determine effects of plane of nutrition followed by feed deprivation on metabolic responses to insulin. Beginning 48 d before expected parturition, cows were fed to either a high plane (HP) or a low plane (LP) of nutrition (162 and 90% of calculated energy requirements, respectively). Cows were subjected to an intravenous glucose tolerance test [GTT; 0.25 g of dextrose/kg of body weight (BW)] on d 14 of treatment and a hyperinsulinemic-euglycemic clamp (HEC; 1 μg/kg of BW/h) on d 15. Following 24 h of feed removal, cows were subjected to a second GTT on d 17 and a second HEC on d 18 after 48 h of feed removal. During the feeding period, plasma nonesterified fatty acid (NEFA) concentrations were higher for cows fed the LP diet compared with those fed the HP diet (163.6 vs. 73.1 μEq/L), whereas plasma insulin was higher for cows fed the HP diet during the feeding period (11.1 vs. 5.2 μIU/mL). Glucose areas under the curve during both GTT were higher for cows fed the LP diet than for those fed the HP diet (4,213 vs. 3,750 mg/dL × 60 min) and was higher during the GTT in the feed-deprived state (4,878 vs. 3,085 mg/dL × 60 min) than in the GTT during the fed state, suggesting slower clearance of glucose during negative energy balance either pre-or post-feed deprivation. This corresponded with a higher dextrose infusion rate during the fed-state HEC than during the feed-deprived-state HEC (203.3 vs. 90.1 mL/h). Plasma NEFA decreased at a faster rate following GTT during feed deprivation compared with that during the fed state (8.7 vs. 2.9%/min). Suppression of NEFA was highest for cows fed the HP diet during the GTT conducted during feed deprivation, and lowest for cows fed the HP diet during the fed-state GTT (68.6 vs. 50.3% decrease from basal). Plasma insulin responses to GTT were affected by feed deprivation such that cows had a much lower insulin response to GTT by 24 h after feed removal (995 vs. 3,957 μIU/mL × 60 min). During the fed-state HEC, circulating concentrations of NEFA were 21% below basal for cows fed the HP diet and 62% below basal for cows fed the LP diet; during feed deprivation, NEFA were 79 and 59% below basal for the HP and LP diets, respectively (diet × HEC). Cows that are fed below energy requirements or are feed deprived have slower clearance of glucose and greater NEFA responses to glucose challenge. Additionally, feed deprivation had a large effect on insulin secretion. Overall, effects of feed deprivation were larger than effects of plane of nutrition.     

Effects of high dietary crude protein on the characteristics of preovulatory follicles in dairy heifers

The objectives were to examine the effect of high dietary crude protein on characteristics of preovulatory follicles in dairy heifers. Eight Israeli-Holstein heifers, 4 fitted with rumen fistula and 4 intact, were assigned to 1 of 3 treatments in a replicated (n = 2) 4 × 3 incomplete Latin square design with 39-d periods. Treatments were: low (6.0%; LP), moderate (13.0%; MP), and high (20.0%; HP) crude-protein diets, containing 1.27 Mcal NE_L/kg dry matter. Diets were based on approximately 66% wheat straw and various proportions of ground corn grain and soybean meal. The estrous cycles of the heifers were synchronized, and 14 d after behavioral estrus, heifers received PGF_2α injections. After a further 40 h, at d 39 of each period, follicular fluid (FF) was aspirated from follicles of diameter >7 mm. The intake of the LP diet was 9% lower than that of MP and HP diets. Rumen ammonia and plasma urea nitrogen concentrations were highest in the HP and lowest in the LP, with intermediate levels in MP diets. No differences were found between treatments in plasma and FF concentrations of glucose and nonesterified fatty acids. High-protein diets increased urea concentrations very similarly in preovulatory FF and in plasma. No differences were observed between diets, in preovulatory follicle diameters and concentrations of androstenedione. However, higher estradiol and progesterone concentrations in FF were observed under the HP than under the MP diet, with no difference between diets in estrogen to progesterone ratio. It can be concluded that high concentrations of urea in plasma, caused by high dietary crude protein, penetrated into preovulatory follicles, but did not impair preovulatory characteristics. This lack of detrimental effects might be attributed to the use in this study of nonlactating heifers, which have fewer nutritional and physiological constraints and eliminate negative effects of potential interactions with high urea on dairy cows’ reproductive systems.     

Effect of a transition diet on production performance and metabolism in periparturient dairy cows

The objectives of this study were to characterize the change in blood metabolites over time, and to evaluate the effect of dietary energy concentration on ketone body accumulation in periparturient cows. Twenty-eight multiparous Holstein cows were listed in order of their anticipated due dates and assigned randomly to 1 of 2 groups: with or without a transition diet. The control group received a nonlactating cow diet [1.54 Mcal/kg of net energy for lactation (NE_L), 10.9% crude protein (CP), 53.1% neutral detergent fiber (NDF)] from 28 d before expected parturition, and a lactation diet (1.77 Mcal of NE_L/kg, 16.8% CP, 29.9% NDF) after parturition. The treatment group received a transition diet (1.71 Mcal of NE_L/kg, 16.8% CP, 35.2% NDF) from 17 d before parturition to 14 d after calving and was fed the same diets as cows in the control group during the third week of lactation. Blood from the coccygeal vein was sampled 3 times per week from 21 d before expected parturition to 21 d postpartum for analysis of glucose, nonesterified fatty acids (NEFA), β-hydroxybutyrate, acetoacetate, acetone, and glycerol. There were no significant differences in dry matter intake, milk yield, milk components, body weight change, and body condition score change during the postcalving period. Plasma concentrations of different ketone bodies changed in parallel, stayed relatively constant precalving, peaked after parturition, and then decreased but remained high compared with concentrations late in gestation. Plasma concentrations of NEFA and glycerol changed in a pattern similar to those of the ketone bodies. Feeding a transition diet resulted in a greater area under the curve (AUC) for glucose in the last 17 d of gestation, but in no effect within the first 21 d in milk. Acetoacetate AUC was greater for treatment cows than for control cows across the first 21 d in milk. The AUC of NEFA and glycerol between d 15 and 21 postpartum were greater for treatment cows than for control cows. Feeding a transition diet both before and after parturition was associated with greater mobilization of adipose tissue and greater exposure to ketone bodies in early lactation compared with abruptly changing to a lactation diet after parturition.     

Interactions of energy and predicted metabolizable protein in determining nitrogen efficiency in the lactating dairy cow

Lactating cows are relatively inefficient in converting dietary N to milk N compared with the efficiency of N use for growth in simple-stomached animals. The majority of productive N losses occur in the postabsorptive system. The aim of the study was to test whether predicted metabolizable protein (MP) and dietary energy exerted independent effects on milk protein synthesis and postabsorptive N efficiency. If true, postabsorptive N efficiency would be expected to be greater when animals are fed high-energy diets. Forty mid-lactation cows (32 multiparous Holstein and 8 primiparous Holstein × Jersey crossbreds) were used in a complete randomized design with a 2 × 2 factorial arrangement of diets. Cows were assigned to 1 of 4 dietary treatments: high-energy, high-protein (HE/HP); high-energy, low-protein (HE/LP); low-energy, high-protein (LE/HP); and low-energy, low-protein (LE/LP). Energy concentrations were 1.55 (HE/HP and HE/LP) or 1.44 (LE/HP and LE/LP) Mcal of net energy for lactation (NE_L)/kg of dry matter (DM). Changes in predicted MP were achieved by feeding diets with 6.6 (HE/HP and LE/HP) or 4.6% (HE/LP and LE/LP) ruminally undegradable protein (DM basis). Ruminally degradable protein was held constant at 10.1% of DM. All cows were fed the HE/HP diet from d 1 to 21 followed by the respective treatments from d 22 to 43 (n = 10). Milk protein yield was reduced as dietary energy was reduced. Milk yield followed a similar pattern as milk protein yield. There was a trend for decreased milk yield as crude protein was reduced. There were no interactions between dietary energy and protein for either milk or protein yield. Plasma amino acid concentrations were not affected by treatment. Milk urea N was affected by energy and protein with a significant interaction (HE/HP = 17.2, HE/LP = 12.2, LE/HP = 21.0, LE/LP = 12.2 mg/dL). Nitrogen efficiency calculated from predicted MP supply was affected by energy and protein supplies with no apparent interaction and ranged from a low of 31% (LE/HP) to a high of 43% (HE/LP). The National Research Council model would predict N efficiency more accurately if a representation of the effects of energy on N efficiency were included in the postabsorptive system.     

Effect of protein level and methionine supplementation on dairy cows during the transition period

Cows experience a significant negative protein balance during the first 30 d of lactation. Given the functional effects of AA on health, especially in challenging periods such as calving, higher levels of protein and specific AA in the diet may act to improve health and feed intake. The response of dairy cows to 3 protein supplementation strategies during the transition period and through the first 45 d in milk was evaluated. The final data set had 39 Holstein cows blocked based on parity (primiparous vs. multiparous) and expected calving and randomly assigned within each block to one of 3 dietary treatments: low protein (LP), high protein (HP), or high protein plus rumen-protected methionine (HPM). Treatments were offered from d ?18 ± 5 to 45 d relative to parturition. Pre- and postpartum diets were formulated for high metabolizable protein (MP) supply from soybean meal, and HP and HPM provided higher MP balance than LP. Preplanned contrasts were LP versus HP+HPM and HP versus HPM. Significance was declared at P ≤ 0.05 and trends at 0.05 < P ≤ 0.10. Cows fed HP and HPM had greater fry matter intake (DMI) prepartum than LP (+2 kg/d), and there was a trend for greater DMI with HPM than with HP (+1.6 kg/d). Body weight and condition score before and after calving did not differ among treatments. High protein (HP and HPM) tended to increase milk yield during the first 45 d of lactation (+1.75 kg/d), increased milk lactose content and urea-N in milk and plasma, tended to increase blood BHB 14 d postpartum, and tended to reduce milk/DMI compared with LP. Blood concentrations of calcium at calving and of glucose, and nonesterified fatty acids pre- and postpartum did not differ. High protein induced lower concentration of plasma IL-1 at calving and lowered blood lymphocytes 21 d postpartum, suggestive of a reduced inflammatory status compared with LP. The concentrations of IL-10, tumor necrosis factor alpha, and other hemogram variables did not differ among treatments. Addition of rumen-protected methionine to the HP diet did not alter milk yield but increased fat and total solids concentrations. The rumen-protected methionine had no effect on blood metabolites and immunity markers, with the exception of increased pre-partum insulin concentrations. The data indicate that dairy cows around calving respond positively to an increase in the supply of MP and to rumen-protected methionine supplementation of the HP diet by increasing intake and improving immune status.     

Short- and longer-term effects of feeding increased metabolizable protein with or without an altered amino acid profile to dairy cows immediately postpartum

The first few weeks after parturition is marked by low, but increasing feed intake and sharply increasing milk production by dairy cows. Because of low intake, the nutrient density of the diet may need to be higher during this period to support increasing milk yields. We hypothesized that feeding higher levels of metabolizable protein (MP) or a protein supplement with rumen-protected lysine and methionine during the immediate postpartum period would increase yields of milk and milk components. Fifty-six Holstein cows (21 primiparous and 35 multiparous) starting at 3 d in milk were used in a randomized block design. In phase 1 (3 through 23 d in milk), cows were fed 1 of 3 diets that differed in supply of MP and AA profile. At 23 d in milk, all cows were moved to a common freestall pen and fed the control diet used in phase 1 for an additional 63 d (phase 2). Diets were formulated using the National Research Council model and were control [16.5% crude protein (CP), 10.9% rumen-degradable protein (RDP), and 5.6% rumen-undegradable protein (RUP)], high MP (HMP; 18.5% CP, 11.6% RDP, 6.9% RUP), and AA (MPAA; 17.5% CP, 10.5% RDP, 7.0% RUP 29.7). The MPAA diet included a proprietary spray-dried blood meal product (Perdue Agribusiness, Salisbury, MD) and contained a model-estimated 7.2 and 2.6% of digestible lysine and methionine (% of MP). The HMP and control diets contained 6.3 and 6.7% digestible lysine and both had 1.8% digestible methionine. In phase 1, diet did not affect milk yield (33.6, 34.7, and 33.2 kg for control, HMP, and MPAA, respectively), dry matter intake (17.8, 18.0, and 18.5 kg/d for control, HMP, and MPAA), or milk protein yield (1.07 kg/d). Feeding additional protein (HMP or MPAA) increased both the concentration and yield of milk fat, and milk protein concentration was greater (3.30 vs. 3.17%) for MPAA compared with the HMP diet. Energy-corrected milk was greater (38.4 and 38.6 vs. 35.3 kg/d, respectively) for MPAA and HP than for the control. Cows fed MPAA had the greatest plasma concentrations of Met and the lowest concentrations of isoleucine, but lysine was not affected by treatment. Feeding additional MP (HMP or MPAA) reduced the concentrations of 3-methylhistidine in plasma, indicating reduced muscle breakdown. Diet effects on milk composition continued after cows were changed to a common diet in that cows fed MPAA the first 3 wk of lactation had greater concentration of milk protein for the entire experiment than cows fed HMP, and cows fed additional MP (HMP and MPAA) during phase 1 had greater concentrations of milk fat for the entire experiment. Increasing dietary protein and AA supply in early lactation had short-term effects on yield of energy-corrected milk and long-term effects on milk composition.     

Effect of energy and protein density of prepartum diets on fat and protein metabolism of dairy cattle in the periparturient period.

To determine if increased nutrient density in prepartum diets improves nutrient balance of peripartum cows, we blocked 40 Holstein cows and 40 heifers by expected date of parturition and assigned them randomly within blocks to one of four treatment diets varying in density of net energy for lactation (NEL) and crude protein (CP). Diets were 1.30 Mcal of NEL/kg and 12.2% CP, 1.49 Mcal of NEL/kg and 14.2% CP, 1.61 Mcal of NEL/kg and 15.9% CP, and 1.48 Mcal of NEL/kg and 16.2% CP. These diets were fed ad libitum from 25 d prepartum until parturition, and all cows were fed the same diet after calving. Increased nutrient-density of prepartum diets did not decrease feed intake. Compared to animals fed the lowest density, those fed the highest density consumed more NEL (20 vs. 14 Mcal/d) and gained more body condition, backfat, and body weight. They also had less nonesterified fatty acids in plasma (176 vs. 233 microM) and more insulin-like growth factor-I in plasma (472 vs. 390 ng/ml) during the last 2 wk prepartum and less triglyceride in liver at parturition (0.9 vs. 1.5%, wet tissue basis). Quadratic effects of energy density were not observed, and the addition of protein in the medium energy diet had no effect. Prepartum diets did not alter any variables during lactation. In conclusion, increasing the energy and protein density up to 1.6 Mcal of NEL/kg and 16% CP in diets during the last month before parturition improves nutrient balance of cattle prepartum and decreases hepatic lipid content at parturition.     

Effects of encapsulated niacin on metabolism and production of periparturient dairy cows

Nicotinic acid (niacin) can suppress lipolysis, but responses to dietary niacin have been inconsistent in cattle. Our aim was to determine if 24 g/d of encapsulated niacin (EN; providing 9.6 g/d of bioavailable nicotinic acid) alters lipid metabolism and productivity of transition cows. Beginning 21 d before expected calving, primiparous (n = 9) and multiparous (n = 13) cows (body condition score of 3.63 ± 0.08) were sequentially assigned within parity to EN (12 g provided with ration twice daily) or control through 21 d postpartum. Liver biopsies were collected on d −21, −4, 1, 7, and 21 relative to parturition. Blood samples were collected on d −21, −14, −7, −4, 1, 4, 7, 14, and 21 relative to parturition. On d 7 postpartum, a caffeine clearance test was performed to assess liver function, and on d 21 to 23 postpartum, blood samples were collected every 8 h to monitor posttreatment nonesterified fatty acid (NEFA) responses. Data were analyzed using mixed models with repeated measures over time. A treatment × time × parity effect was observed on prepartum dry matter intake (DMI), which was caused by a 4 kg/d decrease in DMI of EN-treated multiparous cows compared with control multiparous cows during the final 4 d prepartum. A significant increase in plasma nicotinamide concentration occurred in EN-treated cows on d −7 and 21 relative to parturition. Prepartum glucose concentration decreased in treated animals, with no difference in plasma insulin concentration. Treatment × time × parity effects were detected for NEFA and β-hydroxybutyrate concentrations during the postpartum period. Plasma NEFA peaked at 1,467 ± 160 μM for control animals compared with 835 ± 154 μM for EN-treated animals. After treatments ended on d 21, no evidence was found for a plasma NEFA rebound in either parity group. A treatment × parity × time interaction was detected for liver triglyceride content, indicating a tendency for less liver triglyceride in EN-treated primiparous cows, but caffeine clearance rates were not affected by treatment. No treatment effects were observed for body condition score, body weight, energy balance, or milk or milk component production. A high dose of EN can decrease postpartum plasma NEFA concentration, but may also decrease prepartum DMI.     

Prepartal plane of nutrition, regardless of dietary energy source, affects periparturient metabolism and dry matter intake in Holstein cows

Previous research in our laboratory showed that dietary fat supplementation during the dry period was associated with decreased peripartum hepatic lipid accumulation. However, fat supplementation decreased dry matter (DM) intake and thereby confounded results. Consequently, 47 Holstein cows with body condition scores (BCS) ≤ 3.5 at dry-off were used to determine whether source or amount of energy fed to dry cows was responsible for the decreased hepatic lipid content. Moderate grain- or fat-supplemented diets [1.50 Mcal of net energy for lactation (NE_L)/kg] were fed from dry-off (60 d before expected parturition) to calving at either ad libitum (160% of NE_L requirement) or restricted (80% of NE_L requirement) intakes. Postpartum, cows were fed a single lactation diet for ad libitum intake and performance was measured for 105 d. Prepartum intakes of DM and NE_L were significantly lower for feed-restricted cows as designed. During the first 21 d postpartum, previously restricted cows had higher intakes of DM and NE_L. Body weights and BCS were lower prepartum for restricted cows but groups converged to similar nadirs postpartum. Restricted-fed cows had lower concentrations of glucose and insulin and increased concentrations of NEFA in plasma during the dry period. Peripartum NEFA rose markedly for all treatments but were higher postpartum for cows previously fed ad libitum. Plasma concentrations of NEFA and BHBA remained lower in cows restricted-during the dry period. Postpartum concentrations of total lipid and triglyceride in liver were lower in cows previously feed-restricted. Across dietary treatments, activity of carnitine palmitoyltransferase (CPT) in hepatic mitochondria was lowest at − 21 d, highest at 1 d, and decreased at 21 and 65 d relative to parturition. The activity of CPT at d 1 tended to be higher for previously feed-restricted cows; thereafter, CPT activity declined more rapidly than in cows fed ad libitum. Nutrient intake during the dry period had more pronounced effects on peripartal lipid metabolism and DMI than did composition of the prepartum diet.     

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.     

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 rumen-protected glutamate supplementation during the periparturient period on digestibility,inflammation, metabolic responses,and performance in dairy cows

The objective of this study was to evaluate the effects of feeding rumen-protected glutamate during the periparturient period (d ?21 ± 3 to d 21 ± 3 relative to calving) on apparent total-tract digestibility (ATTD), inflammation, metabolic responses, and production performance of dairy cows. Fifty-two multiparous Holstein cows were blocked by parity, body condition score, and expected calving date, and randomly assigned to one of the experimental diets with rumen-protected monosodium glutamate (RP-Glu; intestinally available Glu = 8.8%) or without RP-Glu (control) at d ?21 ± 3 relative to expected calving date. The RP-Glu was fed at 4% and 3% of dietary dry matter, before and after calving, respectively. Prepartum diets contained 17.1% and 16.5% crude protein, and 13.1% and 13.3% starch, and postpartum diets contained 18.8% and 18.3% crude protein, and 22.5% and 22.7% starch on a dry matter basis, respectively for RP-Glu and control treatments. A subset of 19 cows was used to measure ATTD. Cows fed the RP-Glu had greater ATTD of dry matter (70.6 vs. 69.1%), crude protein (75.1 vs. 72.6%), and ether extract (66.0 vs 61.2%) on d 5 ± 1 after calving. Cows fed the RP-Glu also had greater dry matter intake (15.7 vs. 13.7 kg/d) on d 1 after calving. Cows fed the RP-Glu had greater plasma concentrations of Glu (4.60 vs. 3.89 µmol/dL) and insulin-like growth factor-1 (44.2 vs. 30.1 mg/mL), lower serum concentrations of free fatty acids (670 vs. 981 μEq/L) and total bilirubin (0.22 vs. 0.34 mg/dL), and lower plasma 3-methylhistidine concentration (1.28 vs. 1.50 μmol/dL) on d 4 after calving. However, these treatment effects observed between d 1 and d 5 ± 1 immediately after calving did not continue until d 21 after calving. Concentrations of serum amyloid A, serum haptoglobin, and plasma lipopolysaccharide binding protein were not affected by the treatment. In addition, no differences were observed for serum β-hydroxybutyrate concentration and milk yield during the postpartum period between the 2 groups, and cows fed the RP-Glu had a decreased lactose yield. These findings suggest that feeding RP-Glu during the periparturient period can increase digestive capacity and feed intake, and decrease mobilization of body fat and protein immediately after calving without increasing milk production.     

Effects of genetic merit and varying dietary protein degradability on lactating dairy cows

Eighty two multiparous Holstein cows were blocked by genetic merit (high vs. low) and assigned to one of two treatments [high rumen-undegradable protein (RUP): rumen-degradable protein (RDP) vs. low RUP: RDP] from d 21 before to d 150 after calving to study the effects of these treatments on production and reproductive performance. Diets were isonitrogenous (dry cow 10.5% crude protein; lactating cow 19.3%), isoenergetic (dry cow 10.0 MJ of metabolizable energy (ME); lactating cow 10.9 MJ of ME) and fed as total mixed rations. Feeding more RUP significantly increased dry matter intake and milk yield, reduced body tissue mobilization, and lowered concentrations of serum nonesterified fatty acids (NEFA) and plasma urea. Expression of estrus at first ovulation was improved, first service conception rate was higher, and calving to conception interval was shorter for the high RUP group. Cows of high genetic merit produced more milk, mobilized more body tissue, and had higher concentrations of plasma growth hormone. The dry matter intake and concentrations of blood metabolites did not significantly differ with genetic merit. Expression of estrus at first ovulation was significantly lower for cows of high genetic merit. Serum NEFA concentrations were significantly higher, and estrus was not observed at first ovulation for cows of higher genetic merit fed the low RUP diet. The interaction between dietary RUP and genetic merit was not significant for other measures of performance or fertility. Feeding a low RUP: high RDP diet had negative effects on some aspects of production and reproductive performance. The effects of diet on NEFA concentrations and estrus display were greater in cows of high genetic merit, indicating that potential interactions should be evaluated in future reproductive studies involving protein and fertility.     

Effects of feeding rumen-protected methionine pre- and postpartum in multiparous Holstein cows: Lactation performance and plasma amino acid concentrations

Objectives were to evaluate the effect of feeding rumen-protected methionine (RPM) in pre- and postpartum total mix ration (TMR) on lactation performance and plasma AA concentrations in dairy cows. A total of 470 multiparous Holstein cows [235 cows at University of Wisconsin (UW) and 235 cows at Cornell University (CU)] were enrolled approximately 4 wk before parturition, housed in close-up dry cow and replicated lactation pens. Pens were randomly assigned to treatment diets (pre- and postpartum, respectively): UW control (CON) diet = 2.30 and 2.09% of Met as percentage of metabolizable protein (MP) and RPM diet = 2.83 and 2.58% of Met as MP; CU CON = 2.22 and 2.19% of Met as percentage of MP, and CU RPM = 2.85 and 2.65% of Met as percentage of MP. Treatments were evaluated until 112 ± 3 d in milk (DIM). Milk yield was recorded daily. Milk samples were collected at wk 1 and 2 of lactation, and then every other week, and analyzed for milk composition. For lactation pens, dry matter intake (DMI) was recorded daily. Body weight and body condition score were determined from 4 ± 3 DIM and parturition until 39 ± 3 and 49 DIM, respectively. Plasma AA concentrations were evaluated within 3 h after feeding during the periparturient period [d ?7 (±4), 0, 7 (±1), 14 (±1), and 21 (±1); n = 225]. In addition, plasma AA concentrations were evaluated (every 3 h for 24 h) after feeding in cows at 76 ± 8 DIM (n = 16) and within 3 h after feeding in cows at 80 ± 3 DIM (n = 72). The RPM treatment had no effect on DMI (27.9 vs. 28.0 kg/d) or milk yield (48.7 vs. 49.2 kg/d) for RPM and CON, respectively. Cows fed the RPM treatment had increased milk protein concentration (3.07 vs. 2.95%) and yield (1.48 vs. 1.43 kg/d), and milk fat concentration (3.87 vs. 3.77%), although milk fat yield did not differ. Plasma Met concentrations tended to be greater for cows fed RPM at 7 d before parturition (25.9 vs. 22.9 µM), did not differ at parturition (22.0 vs. 20.4 µM), and were increased on d 7 (31.0 vs. 21.2 µM) and remained greater with consistent concentrations until d 21 postpartum (d 14: 30.5 vs. 19.0 µM; d 21: 31.0 vs. 17.8 µM). However, feeding RPM decreased Leu, Val, Asn, and Ser (d 7, 14, and 21) and Tyr (d 14). At a later stage in lactation, plasma Met was increased for RPM cows (34.4 vs. 16.7 µM) consistently throughout the day, with no changes in other AA. Substantial variation was detected for plasma Met concentration (range: RPM = 8.9–63.3 µM; CON = 7.8–28.8 µM) among cows [coefficient of variation (CV) > 28%] and within cow during the day (CV: 10.5–27.1%). In conclusion, feeding RPM increased plasma Met concentration and improved lactation performance via increased milk protein production.     

Effects of supplementation with ruminally protected choline on performance of multiparous Holstein cows did not depend upon prepartum caloric intake

Objectives were to evaluate the effect of prepartum energy intake on performance of dairy cows supplemented with or without ruminally protected choline (RPC; 0 or 17.3 g/d of choline chloride; 0 or 60 g/d of ReaShure, Balchem Corp., New Hampton, NY). At 47 ± 6 d before the expected calving date, 93 multiparous Holstein cows were assigned randomly to 1 of 4 dietary treatments in a 2 × 2 factorial arrangement. Cows were fed energy to excess [EXE; 1.63 Mcal of net energy for lactation/kg of dry matter (DM)] or to maintenance (MNE; 1.40 Mcal of net energy for lactation/kg of DM) in ad libitum amounts throughout the nonlactating period. The RPC was top-dressed for 17 ± 4.6 d prepartum through 21 d postpartum (PP). After calving, cows were fed the same methionine-balanced diet, apart from RPC supplementation, through 15 wk PP. Liver was biopsied at ?14, 7, 14, and 21 d relative to parturition. Cows fed EXE or MNE diets, respectively, consumed 40 or 10% more Mcal/d than required at 15 d before parturition. Cows fed the MNE compared with the EXE diet prepartum consumed 1.2 kg/d more DM postpartum but did not produce more milk (41.6 vs. 43.1 kg/d). Thus, PP cows fed the EXE diet prepartum were in greater mean negative energy balance, tended to have greater mean concentrations of circulating insulin, fatty acids, and β-hydroxybutyrate, and had greater triacylglycerol in liver tissue (8.3 vs. 10.7% of DM) compared with cows fed the MNE diet prepartum. Cows fed RPC in transition tended to produce more milk (43.5 vs. 41.3 kg/d) and energy-corrected milk (44.2 vs. 42.0 kg/d) without increasing DM intake (23.8 vs. 23.2 kg/d) during the first 15 wk PP, and tended to produce more milk over the first 40 wk PP (37.1 vs. 35.0 kg/d). Energy balance of cows fed RPC was more negative at wk 2, 3, and 6 PP, but mean circulating concentrations of fatty acids and β-hydroxybutyrate did not differ from those of cows not fed RPC. Despite differences in energy balance at 2 and 3 wk PP, mean concentration of hepatic triacylglycerol did not differ between RPC treatments. Feeding RPC reduced the daily prevalence of subclinical hypocalcemia from 25.5 to 10.5%, as defined by concentrations of total Ca of <8.0 mg/dL in serum in the first 7 d PP. Pregnancy at first artificial insemination tended to be greater for cows fed RPC (41.3 vs. 23.6%), but the proportion of pregnant cows did not differ by 40 wk PP. Heifers born from singleton calvings from cows fed RPC tended to experience greater daily gain between birth and 50 wk of age than heifers from cows not supplemented with RPC. Feeding RPC for approximately 38 d during the transition period tended to increase yield of milk for 40 wk regardless of amount of energy consumed during the pregnant, nonlactating period.     

Metabolism of dairy cows as affected by prepartum dietary carbohydrate source and supplementation with chromium throughout the periparturient period

Holstein cows (n = 72) entering second or later lactation were used to determine whether metabolic indices and hepatic capacities for oxidation and gluconeogenesis from propionate are affected by source of carbohydrate in the prepartum diet and chromium-l-methionine (Cr-Met) supplementation throughout the periparturient period. Cows were fed prepartum diets as total mixed rations with the concentrate portion based either on starch-based cereals [high nonfiber carbohydrate (NFC); 1.59 Mcal/kg of net energy for lactation (NE_L), 14.4% crude protein (CP), 40.3% NFC] or nonforage fiber sources (low NFC; 1.54 Mcal/kg of NE_L, 14.5% CP, 33.6% NFC) from 21 d before expected parturition until parturition. After parturition all cows were fed a common lactation total mixed ration (1.74 Mcal/kg of NE_L, 16.5% CP, 40.0% NFC). The Cr-Met was supplemented once daily via gelatin capsule at dosages of 0, 0.03, or 0.06 mg of Cr/kg of BW^0.75. Thus, treatments were in a 2 (carbohydrate source) × 3 (Cr-Met) factorial arrangement. There was no effect of prepartum carbohydrate source on pre- and postpartum plasma concentrations of glucose, nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), insulin, glucagon, or insulin to glucagon ratio. However, cows fed the low NFC diet during the prepartum period tended to have greater plasma NEFA and lower BHBA concentrations postpartum. Liver glycogen concentrations tended to be greater on d 1 postpartum for cows fed low NFC prepartum. Supplementing 0.03 mg/kg of BW^0.75 of Cr as Cr-Met increased prepartum plasma glucose and glucagon concentrations and tended to decrease prepartum plasma NEFA concentrations compared with either 0 or 0.06 mg of Cr/kg of BW^0.75. Postpartum plasma glucose concentrations decreased linearly and glucagon concentrations were increased quadratically by administering increasing amounts of Cr-Met. Supplementing Cr-Met did not affect prepartum plasma concentrations of insulin or BHBA, postpartum NEFA or BHBA, or liver composition. There was an interaction of prepartum carbohydrate source and Cr-Met supplementation such that in vitro hepatic conversion of [1-¹⁴C]propionate to both CO₂ and glucose was similar or increased when Cr-Met was supplemented to cows fed the low NFC diet but decreased when Cr-Met was supplemented to cows fed the high NFC diet. Insulin addition in vitro did not affect hepatic metabolism of propionate on d 1 postpartum. Overall, both the NFC content of the prepartum diet and Cr-Met had only modest effects on metabolic indices in this experiment.     

Metabolic and blood acid-base responses to prepartum dietary cation-anion difference and calcium content in transition dairy cows

Dairy cows commonly undergo negative Ca balance accompanied by hypocalcemia after parturition. A negative dietary cation-anion difference (DCAD) strategy has been used prepartum to improve periparturient Ca homeostasis. Our objective was to determine the influence of a negative DCAD diet with different amounts of dietary Ca on the blood acid-base balance, blood gases, and metabolic adaptation to lactation. Multiparous Holstein cows (n = 81) were blocked into 1 of 3 dietary treatments from 252 d of gestation until parturition: (1) positive DCAD diet and low Ca (CON; containing +6.0 mEq/100 g DM, 0.4% DM Ca); (2) negative DCAD diet and low Ca (ND; ?24.0 mEq/100 g DM, 0.4% DM Ca); or (3) negative DCAD diet plus high Ca supplementation (NDCA; ?24.1 mEq/100 g DM, 2.0% DM Ca). There were 28, 27, and 26 cows for CON, ND, and NDCA, respectively. Whole blood was sampled at 0, 24, 48, and 96 h after calving for immediate determination of blood acid-base status and blood gases. Serum samples collected at ?21, ?14, ?7, ?4, ?2, ?1, at calving, 1, 2, 4, 7, 14, 21, and 28 d relative to parturition were analyzed for metabolic components. Results indicated that cows fed ND or NDCA had lower blood pH at calving but greater pH at 24 h after calving compared with CON. Blood bicarbonate, base excess, and total CO₂ (tCO₂) concentrations of cows in ND and NDCA groups were less than those of cows in CON at calving but became greater from 24 to 96 h postpartum. The NDCA cows had lower blood bicarbonate, base excess, and tCO₂ at 48 h and greater partial pressure of oxygen after calving compared with ND. Cows fed ND or NDCA diets had lower serum glucose concentrations than CON cows before calving but no differences were observed postpartum. Serum concentrations of total protein and albumin were greater prepartum for cows in ND and NDCA groups than for those in CON. Postpartum serum urea N and albumin concentrations tended to be higher for ND and NDCA cows. Cows fed ND or NDCA diets had elevated serum total cholesterol concentration prepartum. During the postpartum period, triglycerides and NEFA of cows fed ND or NDCA diets tended to be lower than those of CON. Cows fed the NDCA diet had greater postpartum total cholesterol in serum and lower NEFA concentration at calving than ND. In conclusion, feeding a prepartum negative DCAD diet altered blood acid-base balance and induced metabolic acidosis at calving, and improved protein and lipid metabolism. Supplementation of high Ca in the negative DCAD diet prepartum was more favorable to metabolic adaptation to lactation in dairy cows than the negative DCAD diet with low Ca.     

Effects of biotin supplementation on peripartum performance and metabolites of Holstein cows

Fifty-two multiparous Holstein cows were randomly assigned to receive 0 or 20 mg of biotin/d starting at an average of 16 d prepartum and then switched to 0 or 30 mg of biotin/d from calving through 70 d postpartum to determine whether supplemental biotin would affect cow performance, hepatic lipidosis, and plasma metabolites. Mean concentration of biotin in plasma sampled weekly was greater in cows fed biotin (4.3 vs. 9.4 nmol/L). Postpartum dry matter intake as a percentage of body weight (3.9% vs. 4.0%), milk production (35.8 vs. 34.8 kg/d), and milk fat concentrations (3.59% vs. 3.69%) were similar between treatment groups. Milk from biotin-supplemented cows tended to have a greater concentration of protein (2.73% vs. 2.83%). Concentrations of plasma nonesterified fatty acids were lower at wk 2 (652 vs. 413 microEq/mL) and 4 (381 vs. 196 microEq/mL) postpartum in cows fed supplemental biotin. However, mean plasma concentrations of beta-hydroxybutyric acid were not affected by biotin supplementation. Mean concentration of plasma glucose was greater for lactating cows fed supplemental biotin (63.4 vs. 66.6 mg/dL). Biopsies of liver were taken at 2, 16, and 30 d postpartum. The triacylglycerol concentration in liver (wet basis) tended to decrease at a faster rate after d 2 postpartum with biotin supplementation compared with control cows. The potential mechanisms that link improved glucose status and decreased lipid mobilization in cows supplemented with biotin warrant further investigation.     

Effects of transition diets varying in dietary energy density on lactation performance and ruminal parameters of dairy cows

Forty cows and twenty heifers were used to study the effects of dietary energy density during late gestation and early lactation on lactation performance and ruminal parameters. A 2 x 2 factorial arrangement of treatments was used. During prepartum (-28 d to calving), animals were fed a low energy density diet [DL; 1.58 Mcal of net energy for lactation (NE(L))/kg, 40% neutral detergent fiber (NDF) and 38% nonfiber carbohydrate (NFC)] or a high energy diet (DH; 1.70 Mcal NE(L)/kg, 32% NDF and 44% NFC). After calving, half of the cows from each prepartum treatment group were assigned to a low energy density diet (L; 1.57 Mcal NE(L)/kg, 30% NDF and 41% NFC) or a high energy density diet (H; 1.63 Mcal NE(L)/kg, 25% NDF and 47% NFC) until d 20 postpartum. After d 20, all cows were fed H until d 70. Animals fed DH had 19.8% greater dry matter intake (DMI; % of body weight) and 21.5% greater energy intake than animals fed DL prepartum and the response was greater for cows compared to heifers. Animals fed DH had lower ruminal pH compared to animals fed DL, but no major changes in volatile fatty acid concentrations were observed. Effects of dietary energy density during prepartum on postpartum production responses were dependent on parity. Primiparous cows fed DL had higher 3.5% fat-corrected milk yield and milk fat production and percentage during the first 10 wk of lactation than those fed DH. Prepartum diet did not affect lactation performance of multiparous cows. Cows fed H had higher DMI and energy intake for the first 20 d of lactation compared to cows fed L. Diets did not affect DMI after the third wk of lactation. Milk production increased faster for cows fed H compared to cows fed L. Animals fed DL-L sequence of treatments tended to have the lowest energy intake during the first 10 wk of lactation. Prepartum treatments did not affect ruminal fermentation characteristics postpartum. Cows fed H had lower ruminal pH and higher propionate concentrations than cows fed L. No prepartum x postpartum interactions were observed for ruminal fermentation parameters. The effects of DH on prepartum DMI did not carry over to the postpartum period or influence early postpartum production. Increasing concentrate content of the diet immediately postpartum instead of delaying the increase until d 21 postpartum is associated with a higher rate of increase.in milk production and higher DMI.