Diet digestibility, rate of passage, and eating and rumination behavior of Jersey and Holstein cows

Diet digestibility and rate of passage, eating and rumination behavior, dry matter intake (DMI), and lactation performance were compared in 6 Jersey and 6 Holstein multiparous cows. Cows were fed gestation diets according to body weight (BW) beginning 7 wk before expected calving and ad libitum amounts of a lactation diet postpartum. Diet digestibility and rate of passage were measured in 5-d periods at wk 5 prepartum and wk 6 and 14 of lactation. Eating and ruminating behavior was measured over 5-d periods at wk 5 and 2 prepartum and wk 2, 6, 10, and 14 of lactation. Milk yield and DMI were higher in Holsteins, but milk energy output per kilogram of metabolic BW (BW^0.75) and intake capacity (DMI/kg of BW) did not differ between breeds. Holsteins spent longer ruminating per day compared with Jerseys, but daily eating time did not differ between breeds. Jerseys spent more time eating and ruminating per unit of ingested feed. The duration and number of meals consumed did not differ between breeds, but the meals consumed by Jerseys were distributed more evenly throughout each 24-h period, providing a more regular supply of feed to the rumen. Feed passed through the digestive tract more quickly in Jerseys compared with Holsteins, suggesting particle breakdown and rumen outflow were faster in Jerseys, but this may also reflect the relative size of their digestive tract. Neutral detergent fiber digestibility was greater in Jerseys, despite the shorter rumen retention time, but digestibility of dry matter, organic matter, starch, and N did not differ between breeds. Utilization of digested N for tissue retention was higher at wk 5 prepartum and lower at wk 14 of lactation in Jerseys. In contrast to numerous published studies, intake capacity of Jerseys was not higher than that of Holsteins, but in the present study, cows were selected on the basis of equal expected milk energy yield per kilogram of metabolic BW. Digestibility of neutral detergent fiber and rate of digesta passage were higher in Jerseys, probably as a consequence of increased mastication per unit of feed consumed in Jerseys and their smaller size.     

Effects of prepartum dry matter intake and forage percentage on postpartum performance of lactating dairy cows

The objective of this research was to determine whether different dry matter intakes (DMI) or forage percentages prepartum would have an impact on postpartum performance. Multiparous Holstein cows (n = 41) received either high (H) or low (L) forage rations that were fed free choice (F) or restricted (R), i.e., HF, HR, LF, and LR. The L rations were higher in net energy of lactation and lower in neutral detergent fiber concentrations. After calving, all cows were fed the same ration ad libitum. Prepartum DMI were 8.0 for R versus 12.4 kg/d for F with LF greater than HF (14.1 vs. 10.7 kg/d). Prepartum treatments did not affect postpartum means for DMI, milk yield, milk protein percentage, body weight, body condition score, or plasma glucose concentrations (overall means 1 to 40 DIM were, respectively, 21.1 kg/d, 34.0 kg/d, 3.03%, 624 kg, 3.2, and 66 mg/dl). However, curves from 1 to 40 DIM showed that DMI and milk yield were slightly higher in early lactation in cows whose DMI had been restricted prepartum but mean milk fat percentage was lower (3.10 vs. 3.42%). Plasma NEFA were higher and insulin lower in H versus L before and after calving. High DMI prepartum, at best, showed no advantage over restricted feeding.     

Body composition and estimated tissue energy balance in Jersey and Holstein cows during early lactation

The rate and extent of estimated energy mobilization and the relationship between fat depth at the rib and thurl and body condition score (BCS) were investigated in Jersey and Holstein cows in early lactation. Twenty-six cows were paired by breed, parity, and calving date, and were individually fed a total mixed ration ad libitum from parturition through 120 d in milk. Feed intake and milk production were measured daily; body weight (BW), BCS, subcutaneous fat depth, milk composition, and concentration of plasma nonesterified fatty acids were measured every 2 wk. Estimated tissue energy balance (TEB) was calculated using 1989 NRC equations. Net energy intake was greater in early lactation for Holsteins compared with Jerseys, 37.8 and 28.2 Mcal/d, respectively. Milk energy was greater for Holsteins relative to Jerseys, 30.5 versus 21.2 Mcal/d. Fat depth and BCS did not differ between breeds. A positive relationship existed between fat depth and BCS for Jerseys; however, there was no significant relationship for Holsteins. The best-fit regression model for predicting TEB for Holsteins and Jerseys in early lactation included week of lactation, milk composition, and BCS. Jerseys remained in negative TEB for a shorter period of time relative to Holsteins. The TEB nadir was -6.19 and -12.9 Mcal/d, for Jerseys and Holsteins, respectively. Expressed as a proportion of metabolic BW (BW(0.75)), net energy intake did not differ between breeds, yet milk energy and estimated tissue energy loss were greater for Holsteins compared with Jerseys.     

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.     

Effect of diets enriched in n-6 or n-3 fatty acids on dry matter intake,energy balance,oxidative stress,and milk fat profile of transition cows

The objective of this study was to determine the effect of dietary supplementation of n-3 polyunsaturated fatty acids (PUFA) and n-6 PUFA on dry matter intake (DMI), energy balance, oxidative stress, and performance of transition cows. Forty-five multiparous Holstein dairy cows with similar parity, body weight (BW), body condition score (BCS), and milk yield were used in a completely randomized design during a 56-d experimental period including 28 d prepartum and 28 d postpartum. At 240 d of pregnancy, cows were randomly assigned to one of the 3 isoenergetic and isoprotein dietary treatments, including a control ration containing 1% hydrogenated fatty acid (CON), a ration with 8% extruded soybean (HN6, high n-6 PUFA source), and a ration with 3.5% extruded flaxseed (HN3; high n-3 PUFA source). The HN6 and HN3 diets had an n-6/n-3 ratio of 3.05:1 and 0.64:1 in prepartum cows and 8.16:1 and 1.59:1 in postpartum cows, respectively. During the prepartum period (3, 2, and 1 wk before calving), DMI, DMI per unit of BW, total net energy intake, and net energy balance were higher in the HN3 than in the CON and NH6 groups. During the postpartum period (2, 3, and 4 wk after calving), cows fed HN3 and HN6 diets both showed increasing DMI, DMI as a percentage of BW, and total net energy intake compared with those fed the CON diet. The BW of calves in the HN3 group was 12.91% higher than those in the CON group. Yield and nutrient composition of colostrum (first milking after calving) were not affected by HN6 or HN3 but milk yield from 1 to 4 wk of milking was significantly improved compared with CON. During the transition period, BW, BCS, and BCS changes were not affected. Cows fed the HN6 diet had a higher plasma NEFA concentration compared with the CON cows during the prepartum period. Feeding HN3 reduced the proportion of de novo fatty acids and increased the proportion of preformed long-chain fatty acids in regular milk. In addition, the n-3 PUFA-enriched diet reduced the n-6/n-3 PUFA ratio in milk. In conclusion, increasing the n-3 fatty acids concentration in the diet increased both DMI during the transition period and milk production after calving, and supplementing n-3 fatty acids was more effective in mitigating the net energy balance after calving.     

Concurrent and carryover effects of feeding blends of protein and amino acids in high-protein diets with different concentrations of forage fiber to fresh cows. 1. Production and blood metabolites

Because of low feed intake during the first weeks of lactation, dietary concentration of metabolizable protein (MP) must be elevated. We evaluated effects of providing additional rumen-undegradable protein (RUP) from a single source or a blend of protein and AA sources during the first 3 wk of lactation. We also evaluated whether replacing forage fiber (fNDF) or nonforage fiber with the blend affected responses. In a randomized block design, at approximately 2 wk prepartum, 40 primigravid (664 ± 44 kg of body weight) and 40 multigravid (797 ± 81 kg of body weight) Holsteins were blocked by calving date and fed a common diet (11.5% crude protein, CP). After calving to 25 d in milk (DIM), cows were fed 1 of 4 diets formulated to be (1) 20% deficient in metabolizable protein (MP) based on predicted milk production (17% CP, 24% fNDF), (2) adequate in MP using primarily RUP from soy to increase MP concentration (AMP; 20% CP, 24% fNDF), (3) adequate in MP using a blend of RUP and rumen-protected AA sources to increase MP concentration (Blend; 20% CP, 24% fNDF), or (4) similar to Blend but substituting fNDF with added RUP rather than nonforage neutral detergent fiber (Blend-fNDF; 20% CP, 19% fNDF). The blend was formulated to have a RUP supply with an AA profile similar to that of casein. A common diet (17% CP) was fed from 26 to 92 DIM, and milk production and composition were measured from 26 to 92 DIM, but individual dry matter intake (DMI) was measured only until 50 DIM. During the treatment period for both parities, AMP and Blend increased energy-corrected milk (ECM) yields compared with the diet deficient in MP based on predicted milk production (40.7 vs. 37.8 kg/d) and reduced concentrations of plasma 3-methyl-His (4.1 vs. 5.3 µmol/L) and growth hormone (9.0 vs. 11.9 ng/mL). Blend had greater DMI than AMP (17.4 vs. 16.1 kg/d), but ECM yields were similar. Blend had greater plasma Met (42.0 vs. 26.4 µmol/L) and altered metabolites associated with antioxidant production and methyl donation compared with AMP. Conversely, the concentration of total essential AA in plasma was less in Blend versus AMP (837 vs. 935 µmol/L). In multiparous cows, Blend-fNDF decreased DMI and ECM yield compared with Blend (19.2 vs. 20.1 kg/d of DMI, 45.3 vs. 51.1 kg/d of ECM), whereas primiparous cows showed the opposite response (15.3 vs. 14.6 kg/d of DMI, 32.9 vs. 31.4 kg/d of ECM). Greater DMI for multiparous cows fed Blend carried over from 26 to 50 DIM and was greater compared with AMP (23.1 vs. 21.2 kg /d) and Blend-fNDF (21.3 kg/d). Blend also increased ECM yield compared with AMP (49.2 vs. 43.5 kg/d) and Blend-fNDF (45.4 kg/d) from 26 to 92 DIM. Few carryover effects of fresh cow treatments on production were found in primiparous cows. Overall, feeding blends of RUP and AA may improve the balance of AA for fresh cows fed high MP diets and improve concurrent and longer-term milk production in multiparous cows. However, with high MP diets, multiparous fresh cows require greater concentrations of fNDF than primiparous cows.     

Effect of prepartum anionic supplementation on periparturient feed intake, health, and milk production

Our objectives were to determine if dietary cation-anion difference (DCAD) and source of anions influence periparturient feed intake and milk production of dairy cattle during the transition period. Diets differed in DCAD (cationic or anionic) and anionic supplement. The 4 diets used prepartum were (1) control [DCAD +20 mEq/100 g of dry matter (DM)], (2) Bio-Chlor (DCAD −12 mEq/100 g of DM; Church & Dwight Co. Inc., Princeton, NJ), (3) Fermenten (DCAD −10 mEq/100 g of DM; Church & Dwight Co. Inc.), and (4) salts (DCAD −10 mEq/100 g of DM). Urine pH was lower for cows that consumed an anionic diet prepartum compared with control. Prepartum diet had no effect on prepartum dry matter intake (DMI) of multiparous or primiparous cows. Postpartum DMI and milk yield for multiparous cows fed anionic diets prepartum were greater compared with those fed the control diet. Postpartum DMI and milk yield of primiparous cows were similar for prepartum diets. Feeding prepartum anionic diets did not affect plasma Ca at or near calving. However, cows fed anionic diets began their decline in plasma Ca later than control cows. Postpartum β-hydroxybutyrate and nonesterified fatty acids were lower for primiparous cows fed prepartum anionic diets compared with those fed the control diet. Prepartum and postpartum plasma glucose concentrations were not affected by prepartum diet for all cows. Liver triglyceride differed for parity by day. Parities were similar at 21 d prepartum, but at 0 d and 21 d postpartum, levels were greater for multiparous cows. Results indicate that decreasing the DCAD of the diet during the prepartum period can increase postpartum DMI and milk production of multiparous cows without negatively affecting performance of primiparous cows.     

Effects of pre- and postpartum dietary starch content on productivity,plasma energy metabolites,and serum inflammation indicators of dairy cows

The objective of this study was to evaluate the effects of the starch content of pre- and postpartum diets on productivity, plasma energy metabolites, and serum markers of inflammation of dairy cows during the calving transition period. Eighty-eight primiparous and multiparous cows were randomly assigned to pre- and postpartum dietary treatments balanced for parity and pretrial body condition score at d 28 ± 3 before expected calving date. Cows were fed either a control [Control; 14.0% starch, dry matter (DM) basis] or high-starch (High; 26.1% starch, DM basis) prepartum diet commencing 28 ± 3 d before expected calving date. Following calving, cows were fed either a high-fiber (HF; 33.8% neutral detergent fiber, 25.1% starch, DM basis) or high-starch (HS; 27.2% neutral detergent fiber, 32.8% starch, DM basis) postpartum diet for the first 20 ± 2 d following calving. Cows fed the High prepartum diet had greater DM intake (12.4 vs. 10.2 kg/d), plasma concentrations of insulin (1.72 vs. 14.2 ng/mL), glucose (68.1 vs. 65.0 mg/dL), and glucagon-like peptide-2 (0.41 vs. 0.32 ng/mL) before parturition, but increased plasma free fatty acid concentration (452 vs. 363 µEq/L) and milk fat yield (1.64 vs. 1.48 kg/d) after parturition. Cows fed the HS postpartum diet had lower plasma free fatty acid (372 vs. 442 µEq/L) and serum haptoglobin (0.46 vs. 0.70 mg/mL) concentrations over a 3-wk period after calving. In addition, there was a tendency for interaction between prepartum and postpartum diets for milk yield, where feeding the HS postpartum diet increased milk yield compared with the HF diet for cows fed the Control prepartum diet (40.8 vs. 37.9 kg/d) but not for cows fed the High prepartum diet. These results suggest that management efforts to minimize the change in diet fermentability during the calving transition by feeding the High prepartum diet, the HF postpartum diet, or both did not increase productivity of dairy cows but increased fat mobilization after calving. Our findings also suggest that feeding high-starch postpartum diets can decrease fat mobilization and serum indicators of systemic inflammation and increase milk production even with the transition from a low-starch prepartum diet.     

Effects of feeding wheat straw or orchardgrass at ad libitum or restricted intake during the dry period on postpartum performance and lipid metabolism

The objectives of this study were to investigate the effects of forage source [wheat straw (WS) or orchardgrass hay (OG)] and total amount of diet dry matter fed [ad libitum or restricted to 70% of predicted dry matter intake (DMI)] prepartum on postpartum performance. The study design was a 2 × 2 factorial design with 10 cows per treatment. Treatments were WS total mixed ration (TMR) ad libitum, OG TMR ad libitum, WS TMR restricted, and OG TMR restricted. The WS TMR (dry matter basis) contained 30% WS, 20.7% corn silage, 10.0% alfalfa hay, 18.2% ground corn, 16.8% soybean meal, and 4.3% molasses mineral mix (14.7% CP, 1.5 Mcal/kg of net energy for lactation, 37.0% neutral detergent fiber). The OG TMR contained 30% OG, 46.2% corn silage, 10.0% alfalfa hay, 9.5% soybean meal, and 4.3% molasses (14.2% CP, 1.5 Mcal/kg of net energy for lactation, 41.0% neutral detergent fiber). Cows received 1 lactation diet after calving (17.7% CP, 1.6 Mcal/kg of net energy for lactation, 27.3% neutral detergent fiber). Total diet DMI prepartum was higher for ad libitum than for restricted as designed, but forage source had no effect on DMI. Total tract apparent digestibilities of DM and NDF were greater for OG than for WS. Postpartum DMI expressed as a percentage of body weight for the first week of lactation was higher for ad libitum than for restricted diets. Postpartum DMI during the first 30 d of lactation was higher for OG than for WS, but no effect was observed for the amount fed prepartum. Milk yield during the first week of lactation was higher for OG than for WS; however, during the first 30 d, 3.5% fat-corrected milk yield and yield of milk fat were highest for OG TMR restricted and WS TMR ad libitum. Prepartum treatments had a limited effect on pre- and postpartum lipid metabolism; however, cows fed WS TMR ad libitum had the highest postpartum β-hydroxybutyrate. Eating behavior was observed by 10-min video scans of 24-h video surveillance for 5 d pre- and postpartum. Prepartum eating time and eating bouts tended to be greater by WS than for OG, and postpartum eating time per kilogram of neutral detergent fiber intake tended to be greater for WS than for OG. Results indicate that forage source and amount of DM fed prepartum affected postpartum performance and tended to alter the behavior of cows in tie-stall barns.     

Effects of induced parturition and estradiol on feed intake, liver triglyceride concentration, and plasma metabolites of transition dairy cows.

The effect of induced parturition and estradiol on feed intake, liver triglyceride, plasma metabolites, and milk yield was evaluated in fifty-six Holstein cows and heifers. Cows were assigned to treatments on d 260 of gestation and were on trial until d 10 postpartum for measurement of dry matter intake (DMI), plasma metabolites, and liver triglyceride and until d 31 postpartum to measure milk yield. Fourteen animals per group (9 cows and 5 heifers) received either a placebo, 1 mg of fenprostalene, 50 mg of estradiol-17 beta benzoate, or both on d 276 of gestation. Cows that received fenprostalene consumed more dry matter (DM) for the last 8 d prepartum than did cows that did not receive fenprostalene (9.6 kg/d vs. 8.5 kg/d, respectively) but consumed less DM for the first 10 d postpartum (10.9 kg/d vs. 13.1 kg/d, respectively). Cows injected with estradiol-17 beta benzoate tended to consume less DM postpartum than did cows not injected with estradiol-17 beta benzoate (11.3 kg/d vs. 12.7 kg/d, respectively). There was no effect of treatment on milk yield; however, a fenprostalene by day interaction resulted from lower milk yield on d 3, 4, 5, 7, and 10 relative to calving in cows that received fenprostalene. Administration of fenprostalene resulted in a delay in the peak plasma nonesterified fatty acid (NEFA) concentration until 2 d after calving. Plasma glucose concentrations were greatest 1 d prior to calving for cows that received fenprostalene, whereas plasma glucose concentrations peaked on the day of calving for cows that did not receive fenprostalene. Liver triglyceride increased over time; however, there was no effect of treatment on liver triglyceride. Calving induction improved DMI for the last 8 d prepartum, but a concomitant decrease in liver triglyceride after calving did not result. Estradiol-17 beta benzoate had no effect on plasma metabolites or liver triglyceride, indicating that the physiological rise in estradiol prior to calving does not have a primary role in lipolysis or hepatic fatty acid metabolism in the dairy cow.     

Concentrate supplementation of a diet based on medium-quality grass silage for 4 weeks prepartum: Effects on cow performance,health, metabolic status,and immune function

Because negative energy balance (EB) contributes to transition-period immune dysfunction in dairy cows, dietary management strategies should aim to minimize negative EB during this time. Prepartum diets that oversupply energy may exacerbate negative EB in early lactation, with detrimental effects on immune function. However, with lower body condition score (BCS) cows, it has been shown that offering concentrates in addition to a grass silage-based diet when confined during an 8-wk dry period resulted in increased neutrophil function in early lactation. The aim of this study was to examine if similar benefits occur when concentrate feeding was restricted to a 4-wk period prepartum. Twenty-six multiparous and 22 primiparous Holstein-Friesian cows were offered ad libitum access to medium-quality grass silage until 28 d before their predicted calving dates (actual mean of 32 d prepartum; standard deviation = 6.4). At this time multiparous cows had a mean BCS of 2.9 (standard deviation = 0.12) and primiparous cows a mean BCS of 3.0 (standard deviation = 0.14) on a 1 to 5 scale. Cows were then allocated in a balanced manner to 1 of 2 treatments (13 multiparous cows and 11 primiparous cows on each treatment): silage only (SO) or silage plus concentrates (S+C) until calving. Cows on SO were offered the same grass silage ad libitum. Cows on S+C were offered an ad libitum mixed ration of the same grass silage and additional concentrates in a 60:40 dry matter (DM) ratio, which provided a mean concentrate DM intake (DMI) of 4.5 kg/cow per d. After calving, all cows were offered a common mixed ration (grass silage and concentrates, 40:60 DM ratio) for 70 d postpartum. Offering concentrates in addition to grass silage during the 4 wk prepartum increased prepartum DMI (12.0 versus 10.1 kg/cow per d), EB (+40.0 versus +10.6 MJ/cow per d), and body weight (BW; 640 versus 628 kg), and tended to increase BCS (3.02 versus 2.97). However, postpartum DMI, milk yield, milk composition, BW change, BCS change, serum nonesterified fatty acid, and β-hydroxybutryrate concentrations, health, and corpus luteum measures were unaffected by treatment. The in vitro assays of neutrophil phagocytosis, neutrophil oxidative burst, and interferon gamma production, conducted on blood samples obtained at d 14 prepartum and d 3, 7, 14, and 21 postpartum, were unaffected by treatment. Primiparous cows had higher phagocytic fluorescence intensity at d 14 prepartum and d 3 and 7 postpartum; a higher percentage of neutrophils undergoing oxidative burst at d 3, 7, and 21 postpartum; and a higher oxidative burst fluorescence intensity at d 14 prepartum and d 7, 14, and 21 postpartum compared with multiparous cows. This suggests that neutrophil function of primiparous cows was less sensitive to the changes occurring during the transition period than that of multiparous cows. In conclusion, offering concentrates during the 4-wk period prepartum had no effect on postpartum DMI, milk yield, body tissue mobilization, EB, measures of neutrophil or lymphocyte function, health, or corpus luteum activity.     

Methane production,rumen fermentation,and diet digestibility of Holstein and Jersey dairy cows being divergent in residual feed intake and fed at 2 forage-to-concentrate ratios

Improving feed efficiency of dairy cows through breeding is expected to reduce enteric methane production per unit of milk produced. This study examined the effect of 2 forage-to-concentrate ratios on methane production, rumen fermentation, and nutrient digestibility in Holstein and Jersey dairy cows divergent in residual feed intake (RFI). Before experimental onset, RFI was estimated using a random regression model on phenotypic herd data. Ten lactating Holstein and 10 lactating Jersey cows were extracted from the herd and allocated to a high or low pre-experimental RFI group of 5 animals each within breed. Cows were fed ad libitum with total mixed rations either low (LC) or high (HC) in concentrates during 3 periods in a crossover design with a back-cross and staggered approach. Forage-to-concentrate ratio was 68:32 for LC and 39:61 for HC. Cows adapted to the diets in 12 to 24 d and feces were subsequently collected on 2 d. Afterward, gas exchange was measured in respiration chambers and rumen liquid was collected once after cows exited the chambers. Pre-experimental RFI was included in the statistical analysis as a class (low and high RFI) or continuous variable. Methane per kilogram of dry matter intake (DMI) was lower for Holsteins than Jerseys and the response to increased concentrate level was more pronounced for Holsteins than Jerseys (27.2 vs.13.8%); a similar pattern was found for the acetate:propionate ratio. However, methane production per kilogram of energy-corrected milk (ECM) was unaffected by breed. Further, total-tract digestibility of neutral detergent fiber was higher for Jerseys than Holsteins. For RFI as a class variable, DMI, methane production regardless of the expression, and digestibility were unaffected by RFI. For RFI as a continuous variable, DMI was lower and methane per kilogram of DMI was higher for cows with negative (efficient) than positive (inefficient) RFI values, and neutral detergent fiber digestibility was higher for Holsteins with negative than positive RFI values, but not for Jerseys. Daily methane production and methane per kilogram of ECM were unaffected by RFI. In conclusion, methane per kilogram of DMI of Jerseys was lowered to a smaller extent in response to the HC diet than of Holsteins. When pre-experimental RFI was used as a continuous variable, higher methane per kilogram of DMI was found for cows with negative RFI than positive RFI values, but not for methane per kilogram of ECM. These findings call for validation in larger studies.     

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.     

Evaluating the inclusion of alfalfa hay in diets fed to multigravid Holstein cows in their transition to early lactation

The objectives of this study were to determine the dry matter intake (DMI), urine pH, Ca concentration in blood, Ca output in urine, and frequency of hypocalcemia in pregnant and nonlactating dairy cows consuming diets containing different hays and acidogenic products during the prepartum period. Eighty pregnant and nonlactating Holstein cows approaching their second or greater calving were fed 1 of 4 experimental diets according to a 2 × 2 factorial arrangement of treatments during the prepartum period (21 d before calving). Diets included either grass hay (GH) or alfalfa hay (AH) and calcium chloride (CL) or polyhalite (PO) as the acidogenic products. All diets had a dietary cation-anion difference (DCAD) below −190 mEq/kg of dry matter (DM). Grass hay contained 75 g/kg crude protein, 749 g/kg neutral detergent fiber, 3.6 g/kg Ca, 0.9 g/kg Na, 18.8 g/kg K, 3.8 g/kg Cl, 1.5 g/kg S, and a cation-anion difference equal to 290 mEq/kg of DM. Alfalfa hay contained 196 g/kg crude protein, 456 g/kg neutral detergent fiber, 15.2 g/kg Ca, 1.6 g/kg Na, 25 g/kg K, 7.7 g/kg Cl, 3.2 g/kg S, and a cation-anion difference equal to 292 mEq/kg of DM. Cows consuming GH tended to consume more DM than cows consuming AH (11.6 vs. 10.8 kg/d) but DMI did not differ between acidogenic products. Urine pH decreased below 6.5 for all diets, although cows consuming the GHPO diet had the highest urine pH. The concentration of Ca in plasma decreased substantially around calving but neither hay type nor acidogenic product affected it. Urinary Ca output was lowest for cows consuming the GHPO diet. No associations existed between dietary treatments and the frequencies of normocalcemia and hypocalcemia. Under the conditions of this study, in which alfalfa and grass hays had similar cation-anion differences, we concluded that the inclusion of alfalfa hay in prepartum diets does not necessarily increase the frequency of hypocalcemia. The cation-anion difference of the alfalfa hay, more than the concentration of potassium alone, may be a key determinant of whether alfalfa hay fits in a prepartum feeding program for prepartum dairy cows. Further research should explore this relationship.     

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

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

Trends in calving ages and calving intervals for dairy cattle breeds in the United States

Trends since 1980 for calving age and calving interval, 2 factors that influence herd life, were examined by parity for 5 breeds of US dairy cattle. Calving data were from cows with records that passed edits for USDA genetic evaluations and were in herds that remained on Dairy Herd Improvement test. First-calf heifers calved at progressively younger ages over time, but the age decline was less for later parities because of longer calving intervals. Breed differences for calving age were evident for all parities; current mean age at first calving ranged from 24 mo for Jerseys to 28 mo for Ayrshires. Mean calving age across all parities declined over time for all breeds, primarily because of increased turnover rate, and ranged from 48 mo for Holsteins to 54 mo for Ayrshires. Across parity, annual increase in calving interval was reasonably consistent (0.90 to 1.07 d/yr) for all breeds except Jersey (0.49 d/yr). Within parity, regressions of calving interval on year were generally similar to overall breed trend. Breed means for first calving interval across time ranged from 390 d for Jerseys to 407 d for Brown Swiss.     

Prepartum dietary management of energy intake affects postpartum intake and lactation performance by primiparous and multiparous Holstein cows

An experiment was conducted to determine the effect of plane of energy intake prepartum on postpartum performance. Primiparous (n = 24) and multiparous (n = 23) Holsteins were randomly assigned by expected date of parturition to 1 of 3 prepartum energy intakes. A moderate energy diet [1.63 Mcal of net energy for lactation (NE_L)/kg; 15% crude protein (CP)] was fed for either ad libitum intake (OVR) or restricted intake (RES) to supply 150 or 80% of National Research Council (2001) energy requirement, respectively, for dry cows in late gestation. To limit energy intake to 100% of NRC requirement at ad libitum dry matter intake (DMI), chopped wheat straw was included as 31.8% of dry matter (DM) in a control diet (CON; 1.21 Mcal of NE_L/kg of DM; 14% CP). Multiparous and primiparous cows assigned to OVR gained body condition during the dry period [initial body condition score (BCS) = 3.3], but were not overconditioned by parturition (BCS = 3.5). Multiparous cows in the OVR group lost more BCS postpartum than multiparous RES or CON cows. Primiparous cows lost similar amounts of BCS among dietary treatment groups postpartum. Addition of chopped wheat straw to CON diets prevented a large decrease in DMI prepartum in both primiparous and multiparous cows. During the first 3 wk postpartum, DMI as a percentage of BW was lower for multiparous OVR cows than for multiparous RES cows. Prepartum diet effects did not carry over through the entire 8-wk lactation period. Because of greater mobilization of body stores, OVR cows had greater milk fat percentage and greater 3.5% fat-corrected milk yield during the first 3 wk postpartum. Multiparous cows assigned to OVR experienced a 55% decrease in energy balance and primiparous cows a 40% decrease in energy balance during the last 3 wk before parturition, compared with CON or RES cows that had little change. Multiparous cows fed OVR had a greater contribution of energy from body energy reserves to milk energy output than either CON or RES cows. Overfeeding energy prepartum resulted in large changes in periparturient energy balance. Even in the absence of overconditioning, a large change in DMI and energy balance prepartum influenced postpartum DMI and BCS loss, especially for multiparous cows. Chopped wheat straw was effective at controlling energy intake prepartum, although primiparous cows did not achieve predicted DMI. Even so, controlling or restricting energy intake in primiparous cows was not detrimental to lactational performance over the first 8 wk of lactation.     

Associations of prepartum plasma cortisol, haptoglobin, fecal cortisol metabolites, and nonesterified fatty acids with postpartum health status in Holstein dairy cows

The association between negative energy balance and health has led to the testing of blood analytes such as nonesterified fatty acids (NEFA) to identify opportunities for improving the management of transition dairy cows. The objective of this study was to evaluate whether prepartum analytes associated with stress (cortisol) or inflammation (haptoglobin) could also identify dairy cattle at increased risk for health complications after calving. Prepartum blood and fecal samples were collected once weekly from 412 Holstein dairy cows on 2 commercial dairy farms (at wk −3, −2, and −1 relative to calving) and analyzed for concentrations of NEFA, haptoglobin (Hp), and cortisol in plasma and cortisol metabolites in feces. Retained placenta (RP), displaced abomasum (DA), subclinical ketosis (SCK), high Hp concentration (HiHp), and death were recorded up to 30 d in milk (DIM), and animals were subsequently categorized into 3 health categories: (1) no disorder of interest (NDI); (2) one disorder (RP, DA, SCK, or HiHp); or (3) more than one disorder (RP, DA, SCK, HiHp) or death. With the exception of prepartum NEFA, no associations were detected between prepartum concentrations of our analytes of interest and the occurrence of one disorder (RP, DA, SCK, or HiHP) by 30 DIM. Haptoglobin concentration tended to be greater during wk −2 and −1 in cows that developed more than one disorder or that died by 30 DIM; however, when calving assistance was included as a covariate in the analysis prepartum, Hp was no longer a significant risk factor for this postpartum health outcome. Primiparous cows with plasma cortisol concentrations >22.2 nmol/L during wk −2 had reduced odds [odds ratio (OR) 0.41; 95% confidence interval (CI) 0.17–0.98] of developing more than one disorder or death by 30 DIM, whereas multiparous cows with plasma cortisol >34.1 nmol/L during wk −2 tended to have greater odds (OR 2.53; 95% CI 0.87–7.37) of developing more than one disorder or death by 30 DIM. Individual variation in daily cortisol secretion patterns and stress responses to the restraint and handling associated with sample collection make prepartum plasma cortisol data and its relationship to postpartum health difficult to interpret. Among multiparous cows, for every 500-unit (ng/g of fecal dry matter) increase in fecal cortisol metabolite concentration during wk −2, cows had increased odds (OR 1.41; 95% CI 1.12–1.79) of developing more than one disorder or dying after calving. For multiparous cows, every 0.15 mmol/L increase in plasma NEFA concentration during any of the 3 wk before calving was associated with an approximately 2-fold increase in the odds of developing more than one disorder or dying by 30 DIM. Fecal cortisol metabolite concentration during the prepartum period did not predict which cows would go on to develop more than one disorder or die within 30 DIM as accurately as prepartum NEFA concentration; therefore, this analyte is not a suitable substitute for NEFA for assessing opportunities to improve herd health.     

Milk production and economic measures in confinement or pasture systems using seasonally calved Holstein and Jersey cows

This 4-yr study examined total lactation performance of dairy cows in two feeding systems: pasture-based and confinement. Spring and fall calving herds were used and each seasonal herd had 36 cows on pasture and 36 cows in confinement with 282 Holstein and 222 Jersey cows included over seven seasonal replicates. Pasture-fed cows received variable amounts of grain and baled haylage depending upon pasture availability. Confinement cows received a total mixed ration with corn silage as the primary forage. Data were collected on milk production, feed costs, and other costs. Pasture-fed cows produced 11.1% less milk than confinement cows. Across treatments, Jerseys produced 23.3% less milk than Holsteins, but calving season and various interactions were not significant. Feed costs averaged $0.95/cow per day lower for pastured cows than confinement cows. Feed costs were lower for Jerseys than Holsteins and for cows calving in spring. Income over feed costs averaged $7.05 +/- 0.34 for confinement Holsteins, $6.89 +/- 0.34 for pastured Holsteins, $5.68 +/- 0.34 for confinement Jerseys, and $5.36 +/- 0.34 for pastured Jerseys; effects of breed were significant but treatment, season, and interactions were not. Economic factors such as labor for animal care, manure handling, forage management, and cow culling rates favored pastured cows. Higher fertility and lower mastitis among Jerseys partially offsets lower income over feed cost compared with Holsteins. Milk production was lower in this study for pasture-based systems but lower feed costs, lower culling costs, and other economic factors indicate that pasture-based systems can be competitive with confinement systems.     

Relationships between body condition,body condition loss,and serum metabolites during the transition period in primiparous and multiparous cows

In the transition period from late gestation to early lactation, dairy cows undergo tremendous metabolic changes. Insulin is a relevant antilipolytic factor. Decreasing serum concentrations of insulin and glucose, increasing serum concentrations of nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHB), and changes in body condition score (BCS) reflect the negative energy balance around calving. This study investigated peripartum metabolic adaptation in 359 primiparous and 235 multiparous German Holstein cows from a commercial dairy herd under field conditions. Body condition score was recorded and blood samples were taken 10 to 1 d prepartum, 2 to 4 d postpartum, and 12 to 20 d postpartum. Generalized mixed models and generalized estimation equations were applied to assess associations between prepartum BCS; BCS changes during the transition period; insulin, glucose, NEFA, and BHB serum concentrations; and milk yield, which was taken from an electronic milk meter from d 6 of lactation. Serum insulin concentrations of multiparous postpartum cows were lower compared with prepartum, and compared with primiparous cows. In general, primiparous cows had lower postpartum NEFA and BHB concentrations than multiparous cows. In primiparous cows, we identified a positive association between prepartum BCS and prepartum serum insulin concentration. Prepartum obese multiparous cows, but not primiparous cows, were characterized by higher postpartum serum NEFA and BHB concentrations and lower milk yield than other cows in the same parity class. Primiparous cows with a smaller degree of BCS loss during the transition period had higher postpartum insulin and lower NEFA concentrations and lower milk yield than other primiparous cows. In conclusion, primiparous cows had less lipolysis and lower milk yield than multiparous cows, associated with higher insulin concentrations. Avoiding high body condition loss during the transition period is a main factor in preventing peripartal metabolic imbalances of glucose and fat metabolism.