Prepartum intake, postpartum induction of ketosis, and periparturient disorders affect the metabolic status of dairy cows

Nutritional management during the dry period may affect susceptibility of cows to metabolic and infectious diseases during the periparturient period. Thirty-five multiparous Holstein cows were used to determine the effect of prepartum intake, postpartum induction of ketosis, and periparturient disorders on metabolic status. Cows were fed a diet from dry-off to parturition at either ad libitum intake or restricted intake [RI; 80% of calculated net energy for lactation (NE_L) requirement]. After parturition, all cows were fed a lactation diet. At 4 d in milk (DIM), cows underwent a physical examination and were classified as healthy or having at least one periparturient disorder (PD). Healthy cows were assigned to the control (n = 6) group or the ketosis induction (KI; n = 9) group. Cows with PD were assigned to the PD control (PDC; n = 17) group. Cows in the control and PDC groups were fed for ad libitum intake. Cows in the KI group were fed at 50% of their intake on 4 DIM from 5 to 14 DIM or until signs of clinical ketosis were observed; then, cows were returned to ad libitum intake. During the dry period, ad libitum cows ate more than RI cows; the difference in intake resulted in ad libitum cows that were in positive energy balance (142% of NE_L requirement) and RI cows that were in negative energy balance (85% of NE_L requirement). Prepartum intake resulted in changes in serum metabolites consistent with plane of nutrition and energy balance. Prepartum intake had no effect on postpartum intake, serum metabolites, or milk yield, but total lipid content of liver at 1 d postpartum was greater for ad libitum cows than for RI cows. The PD cows had lower intake and milk yield during the first 4 DIM than did healthy cows. During the ketosis induction period, KI cows had lower intake, milk yield, and serum glucose concentration but higher concentrations of nonesterified fatty acids and β-hydroxybutyrate in serum as well as total lipid and triacylglycerol in liver than did control cows. Cows with PD had only modest alterations in metabolic variables in blood and liver compared with healthy cows. The negative effects of PD and KI on metabolic status and milk yield were negligible by 42 DIM, although cows with PD had lower body condition score and BW. Prepartum intake did not affect postpartum metabolic status or milk yield. Periparturient disorders and induction of ketosis negatively affected metabolic status and milk yield during the first 14 DIM.     

Effects of late-gestation heat stress independent of reduced feed intake on colostrum,metabolism at calving,and milk yield in early lactation of dairy cows

The objective of this study was to differentiate the effects of acute heat stress (HS) from those of decreased dry matter intake (DMI) during the prepartum period on metabolism, colostrum, and subsequent production of dairy cows. Holstein dairy cows (n = 30) with similar parity and body weight were randomly assigned to 1 of 3 treatments on 45 d before calving: (1) cooled (CL, n = 10) conditions with ad libitum feed intake, (2) HS conditions with ad libitum feed intake (n = 10), and (3) pair-fed cooled (CLPF, n = 10) with reduced DMI similar to the HS group while housed under cooled conditions. The reduction in the amount of feed offered to the CLPF cows was calculated daily as the percentage decrease from the average DMI of HS cows relative to the CL cows. For CLPF and CL cows, barns provided shade, sprinklers, and fans, whereas the HS cows were provided only with shade. Cows in all groups received individually the same total mixed ration. Cows were dried off 60 d before the expected calving. Cows in the HS group and, by design, the CLPF cows had reduced DMI (~20%) during the experiment. Heat stress decreased gestation length, first colostrum yield, and calf birth weight compared with CL and CLPF cows. Milk yield decreased 21% (5 kg) in the HS and 8% (2 kg) in CLPF cows, indicating that reduced feed intake during late gestation accounted for 60% of the total reduced milk yield. The CLPF cows exhibited an elevated NEFA concentration compared with the CL and HS cows. The HS cows had a greater mRNA abundance of HSP70 in the peripheral blood leukocytes at 21 d prepartum compared with the other groups. At calving, the mRNA abundance of HSP70 was greater in HS cows, followed by CLPF, compared with the CL cows. In conclusion, HS during the late gestation period caused metabolism and production differences, which were only partially attributed to reduced feed intake in dairy cows.     

Comparison of red clover and ryegrass silage for dry cows and influence on subsequent lactation performance

The objective of this study was to investigate the use of red clover (RC) silage as a forage for dry dairy cows, primarily relative to its impact on tissue mobilization and repletion during the transition period and performance during the first 10 wk of lactation. Forty multiparous lactating Holstein-Friesian dairy cows were divided into 2 paired groups at 70 d before predicted calving dates; a subset (n = 8) of the cows were used for N and P balance measurements twice during the study. From the start of the experiment until 4 wk before predicted calving date all cows were offered ad libitum access to a ryegrass (RG) silage with no concentrate. At 4 wk before predicted calving date, one group of cows remained on the same diet, and the other group was changed to a diet of ad libitum access to RC silage. There was no difference in feed intakes, but CP intake was higher in cows fed RC silage, whereas ME intake was higher in cows fed RG silage. Cows fed RG silage gained more weight over the last 4 wk of the dry period (DP) than those fed RC silage, but there was no treatment effect on BCS. During the DP fecal N excretion was higher for cows fed RC silage, and there were no treatment differences in urine N excretion or overall N balance. At birth, calves from cows fed the RC silage were heavier. After calving, all cows were offered the same diet of ad libitum access to the same RG silage and a standard lactation concentrate. During the first 10 wk of lactation there was no difference in feed intake between the 2 previous treatment groups, and feed intake reached a maximum at approximately 4 wk of lactation. Cows on the RG treatment during the DP gained more longissimus dorsi muscle depth during the DP and retained it during early lactation. Mobilization of this muscle occurred before calving, indicating repartitioning of amino acids to other body tissues. There were no carryover effects of DP treatment on apparent partitioning of N from diet to milk, urine, or feces at wk 3 of lactation. Feeding RC silage during the DP had almost no impact on subsequent performance of dairy cows in early lactation, probably because the 2 silages were nutritionally very similar.     

Limit-feeding a high-energy diet to meet energy requirements in the dry period alters plasma metabolite concentrations but does not affect intake or milk production in early lactation

Limit-feeding dry cows a high-energy diet may enable adequate energy intake to be sustained as parturition approaches, thus reducing the extent of negative energy balance after parturition. Our objective was to evaluate the effect of dry period feeding strategy on plasma concentrations of hormones and metabolites that reflect energy status. Multiparous Holstein cows (n = 18) were dried off 45 d before expected parturition, paired by expected calving date, parity, and previous lactation milk yield, and randomly assigned to 1 of 2 dry-period diets formulated to meet nutrient requirements at ad libitum or limited intakes. All cows were fed the same diet for ad libitum intake after parturition. Prepartum dry matter intake (DMI) for limit-fed cows was 9.4 kg/d vs. 13.7 kg/d for cows fed ad libitum. During the dry period, limit-fed cows consumed enough feed to meet calculated energy requirements, and ad libitum-fed cows were in positive calculated net energy for lactation (NE_L) balance (0.02 vs. 6.37 Mcal/d, respectively). After parturition, milk yield, milk protein concentration, DMI, body condition score, and body weight were not affected by the prepartum treatments. Cows limit fed during the dry period had a less-negative calculated energy balance during wk 1 postpartum. Milk fat concentration and yield were greater for the ad libitum treatment during wk 1 but were lower in wk 2 and 3 postpartum. Plasma insulin and glucose concentrations decreased after calving. Plasma insulin concentration was greater in ad libitum-fed cows on d −2 relative to calving, but did not differ by dietary treatment at other times. Plasma glucose concentrations were lower before and after parturition for cows limit-fed during the dry period. Plasma nonesterified fatty acid concentrations peaked after parturition on d 1 and 4 for the limit-fed and ad libitum treatments, respectively, and were greater for limit-fed cows on d −18, −9, −5, and −2. Plasma tumor necrosis factor-α concentrations did not differ by treatment in either the pre- or postpartum period, but tended to decrease after parturition. Apart from a reduction in body energy loss in the first week after calving, limit feeding a higher NE_L diet during the dry period had little effect on intake and milk production during the first month of lactation.     

Effect of prepartum dietary energy on condition score, postpartum energy, nitrogen partitions, and lactation production responses

Objectives were to examine the effects of feeding to alter body condition at calving on subsequent full lactation production performance and feed intake, on BW and periparturient blood traits, and on complete energy and N balances and ration digestibility during wk 6, 10, and 14 postpartum. Thirty pluriparous Holstein cows were assigned randomly to two energy intakes from wk 33 of previous lactation through the dry period to create either normal (7.2) or thin (5.8) mean body condition scores at calving (9 = fat, 1 = thin). The thin group was fed 0 kg hominy feed daily; the normal group was fed 2.7 kg daily to supplement forage DM available ad libitum during this period. When compared with the normal group, cows in the thin condition group exhibited less negative body fat balance (-206 vs. -507 g/d); similar milk yield, DM intake, N partitions, and nutrient digestibilities; and lower fat test (3.2 vs. 4.1%) during the balance measurements. Whole blood and serum traits were within normal physiological ranges. Full lactation measurements were similar between treatments except that milk fat percentage was lower and DM intake (as percentage of BW), was higher in the thin condition group. Although mean BW at calving was more (651 vs. 599 kg) for normal condition cows, condition scores and BW were not significantly different at 14 wk postpartum; BW curves indicated similar rates of recovery of weight thereafter. Cows considered underconditioned at parturition mobilized less body fat after calving, resulting in reduced milk fat concentration without significant effects on milk yield, protein, SNF, DM intake, or nutrient utilization.     

Carnitine palmitoyltransferase I in liver of periparturient dairy cows: effects of prepartum intake, postpartum induction of ketosis, and periparturient disorders

Thirty-five multiparous Holstein cows were used to determine the role of mitochondrial carnitine palmitoyltransferase I (CPT I) in liver on peripartal adaptations of fatty acid metabolism. From dry-off to parturition, cows were fed a diet at either ad libitum (n = 17) or restricted intake (RI, 80% of calculated requirements for net energy; n = 18). After parturition, all cows were fed a lactation diet. At 4 d in milk (DIM), cows underwent a physical examination and were classified as healthy (n = 15) or having at least one periparturient disorder (PD; n = 17). Cows in the healthy group were assigned to either a control (n = 6) group or a ketosis induction (KI; n = 9) group. Cows with periparturient disorders were assigned to a third (PDC; n = 17) group. Cows in control and PDC groups were fed for ad libitum intake. Cows in KI were fed at 50% of their respective intake at d 4 postpartum starting from 5 DIM and continuing to signs of clinical ketosis or until 14 DIM; cows then were returned to ad libitum intake. Liver was biopsied at −30 d, 1 d, at signs of clinical ketosis or 14 d, and 28 d relative to parturition. Mitochondria were isolated by differential centrifugation. Activity of CPT I was 5.4 and 7.6 nmol of palmitoylcarnitine formed per min/mg of protein for ad libitum and RI, respectively, at −30 DIM. Sensitivity of CPT I to its inhibitor, malonyl CoA, did not differ between ad libitum and RI cows. Differences in CPT I activity between ad libitum and RI were no longer significant at 1 DIM. Postpartum CPT I activity and malonyl CoA sensitivity at 1 DIM, onset of clinical ketosis or 14 DIM, and 28 DIM were not affected by prepartum intake (ad libitum vs. RI), postpartum health status (healthy vs. PD), or ketosis induction status (control vs. KI vs. PDC). Activity of CPT I was positively correlated with liver total lipid, liver triglyceride, liver triglyceride to glycogen ratio, and serum nonesterified fatty acids. Activity of CPT I and dry matter intake were not correlated. Prepartum intake affected prepartum CPT I activity but not malonyl CoA sensitivity. Neither induction of primary ketosis nor periparturient disorders greatly affected CPT I activity or sensitivity, which indicates that alterations of CPT I may not be a major factor in the etiology of primary ketosis or other periparturient disorders.     

Fibrolytic enzyme supplements for dairy cows in early lactation.

Twenty multiparous lactating Holstein cows in early lactation were used to investigate effects of exogenous fibrolytic enzyme supplementation on dry matter intake, milk production, and digestibility. Cows were blocked according to parity, expected calving date, and milk yield in the previous lactation, and then randomly assigned after calving to two treatments: control or enzyme. The enzyme mixture, which contained mainly xylanase and cellulase activities (Pro-Mote, Biovance Technol. Inc., Omaha, NE), was added to the concentrate to supply 1.3 g/kg of total mixed ration (dry matter basis). The total mixed rations contained 24% corn silage, 15% alfalfa hay, and 61% barley concentrate (dry matter basis) and were offered for ad libitum intake. Enzyme addition did not affect dry matter intake. However, total digestibility of nutrients, determined using Cr2O3, was dramatically increased by enzyme treatment (dry matter, 61.7 vs. 69.1%; neutral detergent fiber, 42.5 vs. 51.0%; acid detergent fiber, 31.7 vs. 41.9%; crude protein, 61.7 vs. 69.8%). Consequently, milk yield tended to increase (35.9 vs. 39.5 kg/d). Percentage of milk fat was lower, and percentages of milk protein tended to be lower for cows fed a diet supplemented with enzymes, such that component yields were similar for cows fed either diet. Energy deficiency was numerically lower for cows fed a diet supplemented with enzymes than for cows fed the control diet (-3.62 vs. -3.33 Mcal/d). Supplementing dairy cow diets with a fibrolytic enzyme mixture has the potential to enhance milk yield and nutrient digestibility of cows in early lactation without changing feed intake.     

Effects of feed intake and sodium bicarbonate on milk production and concentrations of hormones and metabolites in plasma of cows

Eight Holstein cows were used to investigate the effects of DM intake and sodium bicarbonate on lactational performance and concentrations of hormones and metabolites in plasma. Cows were fed a diet with or without 1.0% sodium bicarbonate (dry matter basis) in a switchback design. Four cows were fed ad libitum and four cows were fed approximately 80% of their recommended nutrient requirements by restriction of DM intake throughout the three 21-d periods. Supplementing the diet with sodium bicarbonate increased DM intake of cows fed ad libitum. There was a feed intake by sodium bicarbonate interaction for production of 4% FCM. This interaction may be explained by the difference in DM intake of cows fed ad libitum or restricted amounts of feed and supplemented with sodium bicarbonate. Cows fed restricted amounts of feed had lower milk, milk fat, milk protein, milk SNF, and milk energy yields. Restriction of feed intake increased plasma concentrations of somatotropin and nonesterified fatty acids but decreased concentrations of insulin, triidothyronine, thyroxine, glucagon, and prolactin. In contrast, feeding supplemental sodium bicarbonate did not affect concentrations of hormones or metabolites in plasma at either feed intake.     

Effects of supplementing glycerol and soybean oil in drinking water on feed and water intake, energy balance, and production performance of periparturient dairy cows

The objective of this study was to determine the effects of supplementing glycerol and soybean oil in drinking water on feed and water intake, calculated energy balance, and production performance of periparturient dairy cows. Ninety multiparous Holstein dairy cows were randomly assigned to 1 of 3 treatments: 1) no nutrients supplemented in the drinking water (control); 2) 20 g/L of glycerin supplemented in the drinking water (glycerol); and 3) 10 g/L of soybean oil supplemented in the drinking water (SBO). The trial lasted from 7 d prepartum to 7 d postpartum. Cows were offered a close-up and milking cow TMR for ad libitum intake, pre- and postpartum, respectively. The dry matter intake of cows supplemented with glycerol and SBO was lower than for the control cows throughout the experimental period but not different from each other. Water intake for the control cows was greater than the average for the glycerol and SBO cows prepartum, and greater than for SBO cows but similar to that of glycerol cows postpartum. Glycerol cows consumed more water than SBO cows. There were no differences in energy intake and energy balance of the cows pre- and postpartum. Serum triacylglycerol concentration for glycerol cows was lower than for the control and SBO cows prepartum and was lower than for the SBO cows postpartum. There were no differences in the serum nonesterified fatty acids and glucose concentrations throughout the experiment. There were no differences in the serum β-hydroxybutyrate (BHBA) concentrations at parturition, but serum BHBA concentration of the glycerol cows was greater than for control and SBO cows during the prepartum period. However, during the postpartum period, serum BHBA concentrations of the control cows were greater than for glycerol and SBO cows. There were no differences in calf birth weights or milk yield and composition. Although the glucogenic property of glycerol supplemented in the drinking water at 20 g/L may not have been sufficient to elicit a milk yield response, it did reduce the concentration of BHBA 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.     

Reducing prepartum urine pH by supplementing anionic feed ingredients: Effects on physiological and productive responses of Holstein × Gir cows

This study compared physiological and productive parameters in 3/4 Holstein × 1/4 Gir dairy cows receiving a prepartum concentrate containing ammonium chloride to reduce urine pH near 7.0 (CON; n = 17), or a commercial anionic supplement to reduce urine pH near 6.0 (SUPP; n = 17). Nonlactating, multiparous, pregnant cows were assigned to receive SUPP or CON beginning 21 d before expected date of calving. Cows were maintained in a single drylot pen with ad libitum access to corn silage, and individually received their prepartum concentrate once daily (0800 h) before calving. Cows from both treatments completely consumed their concentrate allocation within 30 min after feeding. Cow body weight and body condition score were recorded once weekly, urine pH measured every 3 d, and blood samples collected on d ?21, ?14, ?9, ?6, and ?3 relative to expected calving date. After calving (d 0), cows were moved to an adjacent drylot pen with ad libitum access to water and a total mixed ration, and were milked twice daily (0600 and 1700 h). Cow body weight and body condition score were recorded once weekly and individual milk production was recorded daily until 30 d in milk (DIM). Blood samples were collected before each milking during the first 5 DIM, as well as at 6, 9, 16, 23, and 30 DIM before the morning milking. Based on actual calving dates, cows received SUPP or CON for (mean ± standard error) 19.2 ± 1.2 and 19.0 ± 0.9 d before calving, respectively. Urine pH was less in SUPP versus CON cows during the last 15 d of gestation (6.12 vs. 7.15, respectively). Milk yield during the first 5 DIM and throughout the experimental period was greater in SUPP versus CON cows (by 20 and 14%, respectively), whereas serum Ca concentrations did not differ between treatments during the first 5 DIM. Serum concentrations of fatty acids were greater in SUPP versus CON cows 3 d before and at calving (by 52 and 22%, respectively), whereas SUPP cows had lower serum glucose and cortisol concentration at calving (by 23 and 27%, respectively). Hence, the SUPP treatment decreased prepartum urine pH near 6.0 in Holstein × Gir dairy cows without depressing concentrate intake compared with CON, although total dry matter intake was not evaluated to fully investigate feed intake responses. Moreover, the SUPP treatment transiently affected serum glucose, fatty acids, and cortisol concentrations near the time of calving, and resulted in greater milk yield during the initial 30 DIM compared with CON.     

Effect of prepartum dry matter intake on liver triglyceride concentration and early lactation.

Depression in feed intake during the final week before calving was hypothesized to be a major factor in the etiology of fatty liver development near parturition. Eleven cows were allowed to eat for ad libitum intake prior to calving (control), and 11 cows were maintained at the same level of DMI recorded during d 21 to 17 prior to calving by force feeding the feed refusals via rumen cannulas. Feed intake by control cows decreased 28% during the final 17 d prior to calving. Lipid triglyceride increased 227 and 75% for control and force-fed cows between d 17 prior to parturition and d 1 following calving. Dry matter intake prior to calving was correlated negatively with liver triglyceride immediately after calving (r = -.80). Plasma glucose concentrations for control and force-fed cows were 63 and 76 mg/dl 2 d prior to calving and also were related closely to liver triglyceride immediately after calving (r = -.50). By d 28 after calving, there were no differences in liver triglyceride between treatments. Cows that were force-fed prior to calving tended to yield milk with greater fat percentage (4.22 vs. 3.88%) and to yield more 3.5% FCM (46.1 vs. 41.7 kg/d) during the first 28 d postpartum.     

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.     

Partial feed restriction decreases growth hormone receptor 1A mRNA expression in postpartum dairy cows

Uncoupling of the growth hormone (GH) axis in early postpartum dairy cows is correlated with a decrease in liver GH receptor (GHR) 1A mRNA and a decrease in liver GH receptor protein. Postpartum recoupling of the GH axis is also correlated with GHR 1A mRNA and GHR protein. We hypothesized that dry matter intake (DMI) partially controls the increase in GHR 1A mRNA postpartum. Prepartum Holstein dairy cows (n = 11) were offered feed ad libitum. After calving, 6 cows were fed 70% of their expected DMI (feed restriction) for 14 d and 5 cows were fed ad libitum (control). Both groups were fed ad libitum after d 14. Liver was biopsied prepartum and on d 1, 7, 14, and 21 postpartum; blood was sampled throughout the experimental period. Rate of increase in postpartum milk production was less for feed-restricted cows. The GHR 1A mRNA decreased from prepartum to d 1 postpartum and subsequently increased. Rate of postpartum increase in GHR 1A mRNA was less in feed-restricted cows. Diminished GHR 1A persisted for at least 7 d after feed-restricted cows returned to ad libitum feeding. Liver insulin-like growth factor-I mRNA concentrations decreased from prepartum to d 1 as well, but were similar for feed restricted and control thereafter. We concluded that DMI partially controls GHR 1A mRNA expression in early postpartum dairy cows and that the decrease in GHR 1A in response to feed restriction persisted for at least 1 wk after ad libitum feeding was restored.     

Effects of parturition and feed restriction on concentrations and distribution of the insulin-like growth factor-binding proteins in plasma and cerebrospinal fluid of dairy cows

Hormones and metabolites act as satiety signals in the brain and play an important role in the control of feed intake (FI). These signals can reach the hypothalamus and brainstem, 2 major centers of FI regulation, via the blood stream or the cerebrospinal fluid (CSF). During the early lactation period of high-yielding dairy cows, the increase of FI is often insufficient. Recently, it has been demonstrated that insulin-like growth factors (IGF) may control FI. Thus, we asked in the present study if IGF-binding proteins (IGFBP) are regulated during the periparturient period and in response to feed restriction and therefore might affect FI as well. In addition, we specifically addressed conditional distribution of IGFBP in plasma and CSF. In one experiment, 10 multiparous German Holstein dairy cows were fed ad libitum and samples of CSF and plasma were obtained before morning feeding on d −20, −10, +1, +10, +20, and +40 relative to calving. In a second experiment, 7 cows in second mid-lactation were sampled for CSF and plasma after ad libitum feeding and again after feeding 50% of the previous ad libitum intake for 4 d. Intact IGFBP-2, IGFBP-3, and IGFBP-4 were detected in plasma by quantitative Western ligand blot analysis. In CSF, we were able to predominantly identify intact IGFBP-2 and a specific IGFBP-2 fragment containing detectable binding affinities for biotinylated IGF-II. Whereas plasma concentrations of IGFBP-2 and IGFBP-4 increased during the periparturient period, IGFBP-3 was unaffected over time. In CSF, concentrations of IGFBP-2, both intact and fragmented, were not affected during the periparturient period. Plasma IGF-I continuously decreased until calving but remained at a lower concentration in early lactation than in late pregnancy. Food restriction did not affect concentrations of IGF components present in plasma or CSF. We could show that the IGFBP profiles in plasma and CSF are clearly distinct and that changes in IGFBP in plasma do not simply correspond in the brain. We thus assume independent control of IGFBP distribution between plasma and CSF. Due to the known anorexic effect of IGF-I, elevated plasma concentrations of IGFBP-2 and IGFBP-4 during the postpartum period in conjunction with reduced plasma IGF-I concentrations may be interpreted as an endocrine response against negative energy balance in early lactation in dairy cows.     

Dietary restriction improved feed efficiency of inefficient lactating cows

The aim of this study was to reduce voluntary dry matter intake (DMI) to increase feeding efficiency of preclassified inefficient (INE) dairy cows through restricted feeding. We studied the effects of dietary restriction on eating behavior, milk and energy-corrected milk (ECM) production, in vivo digestibility, energy balance, and measures of feed efficiency [residual feed intake (RFI) and ECM/DMI]. Before the experiment, 12 pairs of cows were classified as INE. The 2 dietary treatments consisted of ad libitum feeding versus restricted feeding of the same total mixed ration containing 36.5% roughage. Inefficient cows fed the restricted total mixed ration had a shorter eating time and lower meal and visit frequency, but a similar rate of eating, meal size, and meal duration compared with INE cows fed ad libitum. Compared with the INE cows fed ad libitum, restricted INE cows had 12.8% lower intake, their dry matter and neutral detergent fiber digestibility remained similar, and their ECM yield was 5.3% lower. Feed efficiency, measured as RFI, ECM/DMI, and net energy retained divided by digestible energy intake, was improved in the restricted INE cows as compared with the ad libitum cows. Our results show that moderate DMI restriction has the potential to improve feed efficiency of preclassified INE cows.     

Postpartum supplementation of fermented ammoniated condensed whey improved feed efficiency and plasma metabolite profile

Postpartum dietary supplementation of gluconeogenic precursors may improve the plasma metabolite profile of dairy cows, reducing metabolic disorders and improving lactation performance. The objective of this trial was to examine the effects of supplementation with fermented ammoniated condensed whey (FACW) postpartum on lactation performance and on profile of plasma metabolites and hormones in transition dairy cows. Individually fed multiparous Holstein cows were blocked by calving date and randomly assigned to control (2.9% dry matter of diet as soybean meal; n = 20) or FACW (2.9% dry matter of diet as liquid GlucoBoost, Fermented Nutrition, Luxemburg, WI; n = 19) dietary treatments. Treatments were offered from 1 to 45 d in milk (DIM). Cows were milked twice a day. Dry matter intake and milk yield were recorded daily and averaged weekly. Individual milk samples from 2 consecutive milkings were obtained once a week for component analysis. Rumen fluid was collected (n = 3 cows/treatment) at 4 time points per day at 7 and 21 DIM. Blood samples were collected within 1 h before feeding time for metabolite analysis and hyperketonemia diagnosis. Supplementation of FACW improved feed efficiency relative to control; this effect may be partially explained by a marginally significant reduction in dry matter intake from wk 3 to 7 for FACW-supplemented cows with no detected FACW-driven changes in milk yield, milk protein yield, and milk energy output compared with control. Also, there was no evidence for differences in intake of net energy for lactation, efficiency of energy use, energy balance, or body weight or body condition score change from calving to 45 DIM between treatments. Supplementation of FACW shifted rumen measures toward greater molar proportions of propionate and butyrate, and lesser molar proportions of acetate and valerate. Cows supplemented with FACW had greater plasma glucose concentrations in the period from 3 to 7 DIM and greater plasma insulin concentrations compared with control. Plasma nonesterified fatty acid and β-hydroxybutyrate concentrations were decreased in cows supplemented with FACW compared with control cows in the period from 3 to 7 DIM. These findings indicate that FACW may have improved the plasma metabolite profile immediately postpartum in dairy cows. Additionally, supplementation of FACW resulted in improved feed efficiency as accessed by measures of milk output relative to feed intake.     

Addition of straw to the early-lactation diet: Effects on feed intake,milk yield,and subclinical ketosis in Holstein cows

This study evaluated feed intake, milk yield, and subclinical ketosis in dairy cows in early lactation fed 2 different diets postpartum. Cows are typically offered a high-energy ration immediately after calving. We compared a conventional high-energy total mixed ration (TMR) with a transition ration that contained chopped straw. We predicted that adding chopped straw would increase dry matter intake, milk production, and indicators of energy metabolism during the first 3 wk of lactation compared to cows fed a conventional high-energy TMR. We also predicted that carryover effects would be likely for at least 2 wk after treatment ended. A total of 68 mixed-age Holstein cows were enrolled in the study 3 wk before their expected calving. All cows were managed on a single high-forage diet during the dry period. At calving, cows were allocated to 1 of the 2 diets: half to the conventional high-energy TMR (CTMR; n = 34; net energy for lactation = 1.61 Mcal/kg; neutral detergent fiber = 31.7%), and the other half to a high-forage TMR containing chopped wheat straw, equivalent to 4.27% dry matter (STMR; n = 34; net energy for lactation = 1.59 Mcal/kg; neutral detergent fiber = 33.7%) for 3 wk after calving. Cows on STMR were then shifted to CTMR for the next 2 wk to study short-term residual effects on the performance of cows. Treatments were balanced for parity, body condition score, and body weight. Feed intake was measured daily from 2 wk before to 5 wk after calving using automatic feed bins. Blood was sampled twice weekly from 2 wk before to 5 wk after calving, and β-hydroxybutyrate and glucose were measured in serum samples. Subclinical ketosis was identified using a threshold of β-hydroxybutyrate ≥1.0 mmol/L in wk 1 after calving and ≥1.2 mmol/L in wk 2 to 5 after calving. Cows were milked twice daily, and weekly samples (composite samples of morning and afternoon milkings) were analyzed to determine total solids, fat, protein, lactose, and somatic cell count. Data were analyzed in 2 separate periods: the treatment phase (wk +1, +2, and +3) and the post-treatment phase (wk +4 and +5). The addition of straw to the TMR negatively affected the dry matter intake of STMR cows during wk 2 and 3 of lactation. Daily milk yield during the first 5 wk of lactation was lower in STMR cows than in CTMR cows. Concentrations of β-hydroxybutyrate were higher in CTMR cows than in STMR cows during wk 1, but this effect was reversed during wk 2 and 3 of lactation. By 21 d in milk, STMR cows had a greater risk of developing subclinical ketosis than CTMR cows. Adding chopped wheat straw to the TMR during the first 21 d after calving lowered dry matter intake and provided no metabolic or production benefits to lactating dairy cattle.     

Metabolic effects of abomasal L-carnitine infusion and feed restriction in lactating Holstein cows

l-Carnitine is required for mitochondrial fatty acid oxidation, but the effects of carnitine supplementation on nutrient metabolism during dry matter intake depression have not been determined in dairy cows. Studies in other species have revealed responses to l-carnitine that may be of specific benefit to dairy cows during the periparturient period. Eight lactating Holstein cows (132 ± 36 d in milk) were used in a replicated 4 × 4 Latin square experiment with 14-d periods. Treatments were factorial combinations of abomasal infusion of either water or l-carnitine (20 g/d; d 5 to 14) and either ad libitum or restricted intake (50% of previous 5-d dry matter intake; d 10 to 14) of a balanced lactation diet. Liver and muscle biopsies were obtained on d 14 of each period. Feed restriction induced negative balances of energy and metabolizable protein. In feed-restricted cows, carnitine infusion increased 3.5% fat-corrected milk yield compared with those infused with water. Total carnitine concentration in liver was increased in feed-restricted cows infused with carnitine but not in feed-restricted cows infused with water. Carnitine infusion stimulated in vitro oxidation of [1-¹⁴C] palmitate to acid-soluble products and decreased the proportion of [1-¹⁴C] palmitate that was converted to esterified products by liver slices. Feed-restricted cows infused with carnitine had lower liver total lipid concentration and tended to have decreased triglyceride accumulation compared with feed-restricted cows infused with water. Plasma nonesterified fatty acid concentration was not altered by carnitine infusion but was increased by feed restriction; serum β-hydroxybutyric acid was increased by carnitine infusion in feed-restricted cows. In cows fed for ad libitum intake, carnitine infusion affected β-hydroxybutyric acid, insulin, and urea N in serum, liver glycogen concentration, and in vitro alanine oxidation by liver slices, suggesting that hepatic and peripheral nutrient metabolism was influenced. l-Carnitine infusion effectively decreased liver lipid accumulation during feed restriction as a result of greater capacity for hepatic fatty acid oxidation. Further research examining dietary supplementation of l-carnitine during the periparturient period is warranted.     

Effects of supplementing a Saccharomyces cerevisiae fermentation product during the periparturient period on performance of dairy cows fed fresh diets differing in starch content

The objective of this study was to evaluate the effects of supplementing a Saccharomyces cerevisiae fermentation product (SCFP; NutriTek, Diamond V, Cedar Rapids, IA) during the periparturient period (d ?28 ± 3 to 44 ± 3 relative to calving) on dry matter intake (DMI), milk production, apparent total-tract nutrient digestibility, and postpartum ovarian activity of dairy cows fed fresh diets varying in starch content. From d 28 ± 3 before the expected calving date until d 44 ± 3 after calving, 117 Holstein cows were fed diets with SCFP (SCFP; n = 59) or without (control, CON; n = 58). A common, basal, controlled-energy close-up diet (net energy for lactation: 1.43 Mcal/kg; 13.8% starch) was fed before calving. Cows within each treatment (CON or SCFP) were fed either a low- (LS; 22.1% starch) or high-starch (HS; 28.3% starch) diet from d 1 to 23 ± 3 after calving (fresh period), resulting in 4 treatment groups: LS-CON (n = 30), LS-SCFP (n = 29), HS-CON (n = 28), and HS-SCFP (n = 30). All cows were fed the HS diets from d 24 ± 3 to 44 ± 3 after calving (post-fresh period). Cows were assigned to treatment balanced for parity, body condition score, body weight, and expected calving date. Milk yield was higher for cows fed the LS diets compared with those fed the HS diets during the fresh period (34.1 vs. 32.1 kg/d), whereas DMI and 3.5% fat-corrected milk yield (FCM) were not affected by dietary starch content, and LS cows tended to lose more body condition than HS cows (?0.42 vs. ?0.35 per 21 d) during the fresh period. Overall DMI during the close-up and fresh periods did not differ between SCFP and CON cows. However, SCFP supplementation transiently increased DMI on d 1 (13.0 vs. 11.9 kg/d) and 5 (15.5 vs. 14.1 kg/d) after calving compared with CON. During the post-fresh period, SCFP cows tended to eat less than CON cows (19.8 vs. 20.6 kg/d) but had similar 3.5% FCM (44.9 vs. 43.6 kg/d), resulting in greater feed efficiency for SCFP cows (FCM/DMI; 2.27 vs. 2.13). Neither starch content of fresh diets nor SCFP supplementation affected the interval from calving to first ovulation or the incidence of double ovulation. These findings suggest that feeding low-starch diets during the fresh period can increase milk production of dairy cows during the fresh period, and that supplementation of SCFP may increase feed intake around calving and feed efficiency in the post-fresh period.