Interactions of protein levels fed to Holstein cows pre- and postpartum on productive and metabolic responses

The objective of this study was to examine the interaction between levels of dietary crude protein (CP) pre- and postpartum on feed intake, performance, and metabolic status of dairy cows with a 14-d close-up experimental period. Forty multiparous Holstein cows were blocked by expected calving date and previous lactation milk yield at ?14 d relative to expected calving and randomly allocated to receive either a 12.5% CP diet with 3.3% rumen undegraded protein (RUP; 12pre) or a 15.2% CP diet with 5% RUP (15pre) based on dry matter (DM). From d 1 to 21 postpartum, cows within each prepartum group were randomly assigned to receive either a 16.1% CP diet with 4.9% RUP (16post) or a 18.6% CP diet with 6.8% RUP (19post) based on DM. The experiment was conducted as a split-plot design, with CP prepartum being the whole-plot factor and CP postpartum as the subplot factor. Diets were similar in net energy for lactation, and CP levels were increased by replacing grain with a combination of corn gluten meal and fish meal. In prepartum, cows fed the 15pre diet tended to consume more DM than cows fed the 12pre diet (9.65 vs. 9.30 kg/d). Except for blood urea nitrogen (BUN) concentration, no other blood metabolite in prepartum was affected by diets. The interaction between pre- and postpartum CP levels showed that elevating dietary CP from 16post to 19post increased DM intake (15.20 vs. 17.67 kg/d) and milk yield (35.16 vs. 40.26 kg/d) in 12pre cows but not in 15pre cows. Milk fat, protein, and lactose contents were not affected by the interaction between pre- and postpartum CP levels. Feeding 19post compared with 16post increased milk protein (1.28 vs. 1.08 kg/d) and lactose (1.86 vs. 1.61 kg/d) yields in 12pre cows, whereas this effect was not observed in 15pre cows. Milk urea nitrogen was elevated when dietary CP increased from 16post to 19post in 15pre cows (12.98 vs. 14.84 mg/dL) but not in 12pre cows. The concentrations of BUN were greater in 19post cows than in 16post cows for both 12pre (16.31 vs. 13.81 mg/dL) and 15pre (18.44 vs. 14.71 mg/dL) cows. The 19post cows had lower serum fatty acids than 16post cows (0.65 vs. 0.96 mmol/L) in 12pre but not in 15pre. However, a reduction in serum aspartate aminotransferase (AST) concentration was observed in 19post cows compared with 16post cows (68.30 vs. 98.24 U/L) when cows were fed 12pre. For cows fed 15pre, those fed 19post had higher serum AST levels than those fed 16post (86.61 vs. 67.74 U/L) during 21 d of lactation. Body weight and body condition score changes were not affected by interactive effects between pre- and postpartum CP levels, but 19post cows tended (?0.30 vs. ?0.45) to have smaller body condition score losses than 16post cows when fed the 12pre diet. Overall, increasing dietary CP postpartum from 16 to 19% DM improved performance and metabolic status of cows fed 12% CP prepartum. The lack of responses to increased dietary CP postpartum in cows fed 15% CP prepartum suggests that dietary CP postpartum could decrease to 16% DM when cows are fed higher dietary CP prepartum.     

Impact of dietary protein amount and rumen undegradability on intake, peripartum liver triglyceride, plasma metabolites, and milk production in transition dairy cattle

Feeding strategies of transition dairy cows contribute to the risk factors associated with metabolic disorders that limit production in the ensuing lactation. To investigate the effects of prepartum dietary crude protein (CP) concentration and amount of rumen-undegradable protein (RUP) on postpartum health and production, 44 multiparous Holstein cows were blocked by expected calving date and assigned to one of four isoenergetic prepartum rations beginning 28 d prior to expected calving date. Prepartum rations were: 12% CP and 26% RUP, 16% CP and 26% RUP, 16% CP and 33% RUP, or 16% CP and 40% RUP on a dry matter basis. All cows were fed the same postpartum diet (18% CP, 40% RUP) from 1 to 56 d in milk (DIM). Prepartum dry matter intake (DMI) was not different among dietary treatments. Mean postpartum intakes (kg/d) were higher through 56 DIM (P<0.05) for cows fed the 12% CP:26% RUP diet prepartum compared with any of the 16% CP diets (21.8 vs. 19.8, 18.6 and 18.6; 12% CP:26% RUP vs. 16% CP:26% RUP, 16% CP:33% RUP and 16% CP:40% RUP). There was a DIM x prepartum diet interaction (P<0.05) with the greatest effect of the 12% CP:26% RUP diet evident during the first 35 DIM. Cows fed the 12% CP:26% diet during the transition period tended to produce more milk (kg/d) (P = 0.08) than did cows fed any of the 16% CP diets (40.8 versus 37.8, 38.7, and 37.4; 12% CP:26% RUP vs. 16% CP:26% RUP, 16% CP:33% RUP, and 16% CP:40% RUP). Additional protein (12 vs. 16% CP) in the prepartum diet tended to decrease milk protein (P = 0.10) and milk fat yield (P = 0.08) but did not alter percent milk fat, percent milk protein, or MUN. Liver triglyceride (TG) expressed as milligrams of TG per microgram of DNA or percentage of dry matter (DM) on d -28, -14, +1, +28, and +56 relative to calving were not significantly different among treatments. Maximal (P<0.05) infiltration of TG in liver was observed on +1 d when expressed as a percentage of DM and on +28 d when expressed as milligrams of TG per microgram of DNA. Plasma glucose, calcium, urea nitrogen, beta-hydroxybutyrate, and nonesterified fatty acids were not different (P<0.05) among treatments. The data indicate carryover effects of prepartum dietary protein on postpartum intake and milk production, pointing to beneficial effects of maintaining dietary protein for dairy cows in late gestation at 12% CP.     

Crude protein and rumen undergradable protein effects on reproduction and lactation performance of Holstein cows

We conducted a study to determine the effects of excess dietary crude protein (CP) and rumen undegradable protein (RUP) on reproduction and lactation performance of Holstein cows. During each of three yearly replicates, cows were blocked by previous mature equivalent milk production and randomly assigned at calving (n = 47; partum group) or at 42 +/- 21 d postpartum (n = 134; postpartum group) to the following dietary treatments: 1) ryegrass pasture supplemented with a corn and soybean meal grain mix (high CP, moderate RUP); 2) ryegrass pasture mornings and corn silage evenings, supplemented with grain as in diet 1 (moderate CP, moderate RUP control diet), and 3) ryegrass pasture mornings and corn silage evenings, supplemented with a grain mix containing corn, soybean meal, corn gluten meal, and blood meal (moderate CP, high RUP). Dietary CP and RUP concentrations were approximately 23.1, 5.8; 17.7, 5.0; and 17.2, 6.8% of dry matter for diets 1 to 3, respectively. Plasma urea N concentrations were highest in cows fed diet 1 (25.0 mg/dl), intermediate in cows on diet 2 (20.1 mg/dl), and lowest in cows on diet 3 (18.5 mg/dl). Cows fed excess dietary protein (diet 1) exhibited lower first breeding pregnancy rates (24.1 vs. 41.0%) and lower overall pregnancy rates (53.4 vs. 75.4%) than did cows fed diet 2, increasing time nonpregnant by an average of 15.1 d per cow. Reproductive performance was similar between cows fed diets 2 and 3. Mean fat-corrected milk (FCM) yield was not affected by protein concentration (diet 1 vs. 2); however, partum group cows that received supplemental RUP (diet 3) produced more 3.5% FCM than controls in early lactation. Feeding grain diets that contained excess dietary protein impaired the reproductive performance of dairy cows grazing ryegrass.     

Effect of dietary rumen-protected choline in lactating dairy cows

Two experiments were conducted to test the effects of graded amounts of rumen-protected choline on milk yield and composition in lactating dairy cows fed 40% corn silage and 60% concentrate diets (DM basis). In Experiment 1, 48 Holstein cows were fed 0, .078, .156, and .234% rumen-protected choline (choline chloride basis) from wk 5 to 21 postpartum. Increasing choline had no effect on DMI and tended to increase milk yield only from 1 to 2.2 kg/d. Milk fat percentage was reduced in the .078% choline treatment and increased to control levels thereafter with .156 and .234% choline. In Experiment 2, 16 Holstein cows in midlactation were assigned randomly to either 13.0 or 16.5% dietary CP (DM basis). Within CP concentration, cows were fed 0, .08, .16, and .24% rumen-protected choline in a replicated 4 x 4 Latin square design. Dietary protein had no effect on milk yield, although milk protein percentage and yield were increased .25 percentage units and 63 g/d, respectively, by increased dietary CP. Increasing dietary choline to .24% linearly increased milk yield 2.6 kg/d, although it had no consistent effects on milk fat or protein percentage. There was only a slight tendency for greater responses in milk yield to dietary choline with lower dietary CP. Data from these experiments confirm earlier results with postruminal choline infusions, suggesting that choline may be a limiting nutrient for milk production.     

Effect of prepartum dietary protein level on performance of primigravid and multiparous Holstein dairy cows

This study compared the effects of two levels of crude protein (CP) fed during late gestation on the performance, blood metabolites, and ovarian activity of Holstein cows. One-hundred and six cows (42 primigravid and 64 multiparous) 32 d before calving were divided into two groups and fed diets containing moderate (12.7% CP, 36% rumen undegradable protein, (RUP) or high (14.7% CP, 40% RUP) protein. Higher prepartum CP diet increased milk production during the first 120 d in milk (DIM), but most of that effect was detected for the primigravid cows. Primigravid cows fed the prepartum diet higher in protein produced 2.0 kg/d more milk and 3.1 kg/d more 3.5% fat-corrected milk (FCM) during early lactation. Yields of milk fat and protein in early lactation were also increased by the high prepartum CP diet fed to primigravid cows. During the complete lactation, the response to prepartum dietary protein differed between primigravid and multiparous cows. Yields of milk, 3.5% FCM, and milk fat and protein were not affected by the prepartum diet for primigravid cows, but decreased for multiparous cows fed the high protein diet. However, primigravid cows fed the high prepartum protein diet had a higher 305-d mature equivalent milk yield. Colostrum composition, blood metabolites, ovarian activity, and disease incidence were not influenced by prepartum protein. Data from this study suggest that the current prepartum protein recommendation seems to be adequate for multiparous cows, but late-gestation primigravid cows might benefit from diets with a CP content above 12.7%.     

Supplemental dietary protein for grazing dairy cows: effect on pasture intake and lactation performance

One hundred twenty-four cows (92 multiparous and 32 primiparous) were used to evaluate the effect of grain supplements containing high crude protein [(22.8% CP, 5.3% rumen undegradable protein (RUP), dry matter basis], moderate CP (16.6% CP, 6.1% RUP), and moderate CP with supplemental RUP (16.2% CP, 10.8% RUP) on lactation performance of Holstein cows rotationally grazing annual ryegrass-oat pastures. Supplemental protein was provided by solvent extracted soybean meal in the high CP and moderate CP supplements and as a corn gluten meal-blood meal mixture (2.8:1) in the moderate CP, high RUP supplement. Cows were blocked according to previous mature milk equivalent production and calving date (partum group; 0 d in milk or postpartum group; 21 to 65 d in milk) and randomly assigned to dietary treatments. Grain was individually fed, at approximately a 1:3 grain to milk ratio, before a.m. and p.m milkings. The study was replicated during two grazing seasons that averaged 199 d. Cows had ad libitum access to bermudagrass hay while on pasture (dry matter intake = 1.3 kg/d). Protein supplementation had no effect on study long pasture dry matter (12.7 +/- 1.0 kg/d) or total dry matter (23.9 +/- 1.2 kg/d) consumption. Protein concentration did not affect actual milk yield of either calving group (high CP vs. moderate CP); however, postpartum group cows receiving high CP grain supplements maintained greater milk fat concentrations (3.34 vs. 3.11%), which led to higher fat-corrected milk (FCM) yields than control cows receiving moderate CP grain diets (30.3 vs. 28.9 kg/d). Crude protein concentration in milk of high CP-supplemented, postpartum group cows was also higher than moderate CP cows (3.42 vs. 3.27%). Additional RUP did not increase FCM yield above that generated by moderate CP grain diets for partum (34.3 vs. 32.9 kg/d) or postpartum-group cows (28.9 vs. 28.2 kg/d). Increasing CP concentration of grain supplement did not affect milk yield of Holstein cows grazing immature winter annual pastures. Supplementing additional RUP was without benefit, indicating that in this study energy deprivation may have been the major nutritional constraint for high-producing dairy cows grazing lush pastures.     

Short commuunication: Effect of dietary protein depletion and repletion on skeletal muscle calpastatin during early lactation

Sixteen multiparous Jersey cows were assigned at calving to one of 4 dietary treatments. An 18% crude protein (CP) diet was fed as a total mixed ration through 30 d in milk (DIM), and beginning at 31 DIM a 9, 12, 15, or 18% CP diet was fed through 58 DIM (depletion). All cows were then fed the 18% CP diet until 84 DIM (repletion). Muscle biopsies were taken under local anesthesia at 49 and 84 DIM from the semitendinosus muscle. Milk production, DMI, and milk component contents were measured. Calpain and calpastatin contents of muscle taken at biopsy were evaluated using Western blotting techniques. Milk production and milk protein content were reduced during the depletion period by decreasing dietary protein. Diet had no effect on milk fat content or DMI. During repletion, DMI was affected by dietary treatment. Western blots of muscle extracts indicated no differences in calpain content at any stage of the experiment or in calpastatin content of muscle at 49 DIM. However, at 84 DIM, calpastatin (135 kDa) was lower or undetectable in cows fed either the 9 or 12% CP diets from 31 to 59 DIM. Bands for a 110-kDa degradation product of calpastatin were present in some cows fed the 9, 12, and 15% CP diets during the depletion period. Results indicate a change in skeletal muscle calpain/calpastatin proteolytic system during protein repletion following depletion with diets of less than 15% CP during early to peak lactation in dairy cows.     

Effects of providing two forms of supplemental methionine to periparturient Holstein dairy cows on feed intake and lactational performance

Eighteen primiparous and 42 multiparous Holstein cows were blocked according to parity and expected calving date and assigned randomly to 1 of 3 dietary treatments: 1) a basal diet (negative control), 2) the basal diet plus 2-hydroxy-4-methylthio butanoic acid isopropyl ester (MetaSmart, Adisseo Inc., Antony, France), or 3) the basal diet plus rumen-protected Met (Smartamine M, Adisseo Inc., Alpharetta, GA). Treatments were initiated 21 d before expected calving and continued through 140 d postpartum. Diets were similar in ingredient and chemical composition, except for the content of Met in metabolizable protein. MetaSmart [0.35% prepartum and 0.54% postpartum in diet dry matter (DM)] and Smartamine M (0.06% prepartum and 0.10% postpartum in diet DM) were added to the basal diet in amounts needed to achieve a 3.0:1 ratio of Lys to Met in metabolizable protein. Prepartum DM intake (DMI; 13.5 kg/d), body weight (687 kg), body condition score (3.81), postpartum milk yield (42.0 kg/d), milk fat yield (1,549 g/d), milk fat content (3.66%), milk true protein yield (1,192 g/d), and milk urea N content (12.9 mg/dL) were not different among treatments. Postpartum DMI and body condition score were greater and the ratios of milk:DMI and milk N:feed N were less for cows fed the MetaSmart diet than for cows fed the control and Smartamine M diets. Milk protein content was greater for the Smartamine M (2.87%) and MetaSmart (2.81%) treatments than for the control treatment (2.72%). Concentrations of Met and Met + Cys in total plasma AA were different among treatments, with values for the Smartamine M treatment being the highest, followed by the MetaSmart and control treatments. The results indicated that both MetaSmart and Smartamine M are effective in providing metabolizable Met, but clarification of their relative contributions to metabolizable Met is still needed.     

Influence of dietary protein and supplemental niacin on lactational performance of cows fed normal and low fiber diets.

Forty-seven cows (24 primiparous) were assigned to one of four normal (20.5%) ADF diets for wk 2 to 5 postpartum. Dietary treatments in a 2 x 2 factorial design were diets of 13.8 versus 18.8% CP and 0 versus 12 g/d of niacin per cow. During wk 6 to 13 postpartum, cows were fed low (11.8%) ADF diets while maintaining CP and niacin treatments. Low CP diets contained solvent-extracted soybean meal; rumen soybean meal with enhanced undegradable protein was used in high CP diets. High CP diets increased milk protein percentage in multiparous cows and yields of milk, 4% FCM, fat, protein, and SNF in primiparous cows during the normal fiber period. High dietary CP also increased yields of 4% FCM, fat, protein, and SNF in primiparous cows fed normal fiber diets. When switched to low fiber diets, primiparous cows fed high CP diets decreased more in 4% FCM and fat yields than those fed low CP. Primiparous cows fed niacin decreased more in 4% FCM than controls. High dietary CP increased DMI in primiparous cows fed normal fiber diets, but those fed low CP diets increased more in DMI when switched to low fiber diets. Supplemental niacin appeared to interact with dietary CP in multiparous cows, increasing blood glucose and decreasing blood beta-hydroxybutyrate and NEFA concentrations with the high CP, normal fiber diet. Increased dietary CP improved yields of milk and milk components in primiparous cows.     

Effects of dietary crude protein concentration and degradability on milk production responses of early, mid, and late lactation diary cows

Three experiments were conducted to investigate the effect of crude protein (CP) concentration and ruminally undegraded protein (RUP) concentration on milk production and composition of dairy cows at three different stages of lactation. Experiments 1, 2, and 3 using 39, 40, and 39 Holstein cows were conducted for cows in early (wk 4 to 14 postpartum), mid (wk 19 to 29), and late (wk 34 to 44) lactation, respectively. Cows were assigned to one of four corn-based diets: high CP, medium RUP (control); low CP, low RUP; low CP, medium RUP; and low CP, high RUP. Percentages of CP in the high and low CP diets were, respectively, 17.4 and 15.2 for Experiment 1, 15.3 and 13.3 for Experiment 2, and 14.2 and 12.6 for Experiment 3. The RUP concentrations (percentages of CP) for low, medium, and high diets averaged 35.5, 41.4, and 46.5%, respectively. For Experiment 1, production of milk, 4% fat-corrected milk, milk fat, and milk protein was increased by the high protein diets versus the low protein diets. Production of milk and fat-corrected milk increased linearly as RUP in the diet increased. During Experiment 2, lactational responses were not affected by treatment. During Experiment 3, dry matter intake, body weight, and body weight change increased for cows fed the high protein diets versus those same measurements for cows fed the low protein diets. Milk fat and milk protein percentage decreased linearly as RUP in the diet increased. Because there was no effect of diet on milk production, decreasing CP in diets fed to cows in mid or late lactation can reduce the cost of the diet and waste N excreted from the cow.     

Performance of dairy cows fed diets formulated at 2 starch concentrations with either canola meal or soybean meal as the protein supplement

This study was designed to evaluate the effects of substituting corn grain with nonforage fiber sources in diets containing soybean meal (SBM) or canola meal (CM) as the primary protein source. Sixteen Holstein cows were assigned to a replicated 4 × 4 Latin square design with 4 periods of 28 d each. Treatments were arranged as a 2 × 2 factorial with 2 protein sources (SBM and CM) and 2 dietary starch concentrations (21 and 27% dry matter, DM). Diets were formulated to contain 16.5% CP, and the 21% starch diets were obtained by replacing corn grain with soybean hulls and beet pulp. Protein source × starch interactions were observed for DM intake (DMI), milk fat and protein concentrations, milk protein yield, milk urea nitrogen, and feed efficiency. Cows fed CM diets had a higher DMI when dietary starch concentration was 27% compared with 21%, but those cows had DMI similar to that of cows on SBM diets regardless of the starch concentration. Milk fat percentage was decreased in cows fed CM with 27% starch compared with cows fed CM with 21% starch and cows fed SBM with 27% starch. Milk protein percentage and yield and milk lactose percentage were least in cows fed CM with 21% starch compared with the other 3 diets, but feed efficiency was greater for cows fed CM with 21% starch. Milk urea nitrogen was least in cows fed CM with 27% starch compared with the other 3 diets. Cows fed diets with 27% starch produced 2.5 kg/d more milk and 1.9 kg/d more energy-corrected milk compared with cows fed 21% starch. Digestibility of DM and organic matter was higher in cows fed SBM diets than in cows on CM diets, and cows fed 27% starch showed greater DM and organic matter digestibility than cows on 21% starch. Digestibility of neutral detergent fiber and acid detergent fiber was greater in diets with SBM than in those with CM. Molar proportion of acetate was the lowest for cows fed CM with 21% starch compared with cows fed SBM with 21% starch, with the remaining cows fed being intermediate and similar. However, propionate was highest for cows fed CM with 21% starch than for cows fed SBM with 21% starch, but the remaining treatments were intermediate and similar. Isobutyrate was greater for cows fed CM with 21% starch, which resulted in the lowest acetate:propionate ratio compared with cows fed the remaining treatments. Overall, we confirmed that the interaction of protein with starch in CM diets can sustain similar cow performance as with the SBM diets. Those making decisions about starch concentration and protein source should consider feed price when SBM or CM and different starch levels are being formulated in diets for lactating dairy cows.     

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

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

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.     

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.     

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. 2. Protein balance and body composition

Increasing the supply of metabolizable protein (MP) and improving its AA profile may attenuate body protein mobilization in fresh cows and lead to increased milk production. Increasing the concentration of rumen-undegradable protein (RUP) to increase MP supply and replacing RUP sources from forages instead of nonforage fiber sources may further decrease tissue mobilization if it improves dry matter intake (DMI). Our objective was to determine whether increasing MP concentrations and improving the AA profile at the expense of either nonforage or forage fiber (fNDF) would affect MP balance and empty body (EB) composition (measured using the urea dilution method) in early postpartum dairy cows of different parities. In a randomized block design, 40 primigravid [77 ± 1.5 kg of EB crude protein (CP) at 8 ± 0.6 d before calving] and 40 multigravid (92 ± 1.6 kg of EB CP at 5 ± 0.6 d before calving) Holsteins were blocked by calving date and fed a common prepartum diet (11.5% CP). After calving to 25 d in milk (DIM), cows were fed 1 of 4 diets: (1) a diet deficient in MP meeting 87% of MP requirements (DMP, 17% CP, 24% fNDF), (2) 104% of MP requirements using primarily soy protein to make MP adequate (AMP, 20% CP, 24% fNDF), (3) 110% of MP requirements using a blend of proteins and rumen-protected (RP) AA to make MP adequate (Blend, 20% CP, 24% fNDF), or (4) a diet similar to Blend but substituting added RUP for fNDF rather than nonforage NDF (Blend-fNDF, 20% CP, 19% fNDF). Blend was formulated to have a RUP supply with a similar AA profile to that of casein. Cows were fed a common diet (16.3% CP) from 26 to 50 DIM. Calculated MP balance (supply – requirements) was less than zero for DMP and Blend-fNDF from 1 to 4 wk of lactation (WOL), whereas that for AMP was positive from 1 to 4 WOL and that for Blend was close to zero from 3 to 4 WOL. Daily MP balance was greater from 5 to 7 WOL for DMP compared with AMP and Blend (100 vs. 22 g/d). From ?7 to 7 d relative to calving, losses of EB CP were greater for DMP than for AMP and Blend (?121 vs. average of 11 g/d). From 7 to 25 DIM, cows fed AMP (?139 g/d) and Blend-fNDF (?147 g/d) lost EB CP but cows fed Blend (?8 g/d) maintained EB CP. Increased DMI for Blend versus AMP led to reduced losses of EB lipid in primiparous cows from 7 to 25 d relative to calving (?1.0 vs. ?1.3 kg/d of EB lipid), whereas lipid mobilization was similar in multiparous cows (average ?1.1 kg of EB lipid/d). By 50 DIM, EB lipid and CP were similar across treatments and parities (average 60.2 kg of EB lipid and 81.6 kg of EB CP). Overall, feeding fresh cows a high MP diet with a balanced AA profile improved DMI and attenuated EB CP mobilization, which could partly explain positive carryover effects on milk production for multiparous cows and reduced lipid mobilization for primiparous cows.     

Supplemental Smartamine M or MetaSmart during the transition period benefits postpartal cow performance and blood neutrophil function

The onset of lactation in dairy cows is characterized by severe negative energy and protein balance. Methionine availability during this time for milk production, hepatic lipid metabolism, and immune function may be limiting. Supplementing Met to peripartal diets with adequate Lys in metabolizable protein (MP) to fine-tune the Lys:Met ratio may be beneficial. Fifty-six multiparous Holstein cows were fed the same basal diet from 50 d before expected calving to 30 d in milk. From −50 to −21 d before expected calving, all cows received the same diet [1.24 Mcal/kg of dry matter (DM), 10.3% rumen-degradable protein, and 4% rumen-undegradable protein] with no Met supplementation. From −21 d to expected calving, the cows received diets (1.54 Mcal/kg of DM, 10% rumen-degradable protein, and 5.1% rumen-undegradable protein) with no added Met (control, CON; n = 14), CON plus MetaSmart (MS; Adisseo Inc., Antony, France; n = 12), or CON plus Smartamine M (SM; Adisseo Inc.; n = 12). From calving through 30 d in milk, the cows received the same postpartum diet (1.75 Mcal/kg of DM and 17.5% CP; CON), or the CON plus MS or CON plus SM. The Met supplements were adjusted daily and top-dressed over the total mixed ration at a rate of 0.19 or 0.07% (DM) of feed for MS or SM. Liver tissue was collected on −10, 7, and 21 d, and blood samples more frequently, from −21 through 21 d. Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC) with the preplanned contrasts CON versus SM + MS and SM versus MS. No differences in prepartal DM intake (DMI) or body condition score were observed. After calving, body condition score was lower (2.6 vs. 2.8), whereas DMI was greater (15.4 vs. 13.3 kg/d) for Met-supplemented cows. Postpartal diet × time interactions were observed for milk fat percentage, milk fat yield, energy-corrected milk:DMI ratio, and energy balance. These were mainly due to changes among time points across all treatments. Cows supplemented with either Met source increased milk yield, milk protein percentage, energy-corrected milk, and milk fat yield by 3.4 kg/d, 0.18% units, 3.9 kg/d, and 0.18 kg/d, respectively. Those responses were associated with greater postpartum concentration of growth hormone but not insulin-like growth factor 1. There was a diet × time effect for nonesterified fatty acid concentration due to greater values on d 7 for MS; however, liver concentration of triacylglycerol was not affected by diet or diet × time but increased postpartum. Blood neutrophil phagocytosis at 21 d was greater with Met supplementation, suggesting better immune function. Supplemental MS or SM resulted in a tendency for lower incidence of ketosis postpartum. Although supplemental MS or SM did not decrease liver triacylglycerol, it improved milk production-related traits by enhancing voluntary DMI.     

Effect of total and rumen undegradable protein on the performance of cows fed low fiber diets.

Twelve multiparous and 18 primiparous Holstein cows were fed a 17.3% CP, 21.0% ADF diet during wk 2 through 6 postpartum. Cows then were assigned from wk 7 through 14 to one of three low fiber (10.7% ADF) dietary treatments containing either 14.4 or 18.7% CP, the latter with or without a soybean meal enhanced with rumen undegradable protein. Treatments had no effect on milk yield or composition in multiparous cows, although milk fat percentage was not depressed in multiparous cows receiving the low fiber diets. The soybean meal diet enhanced with rumen undegradable protein increased yields of milk, 4% FCM, fat, protein, and DMI compared with the 14.4% CP diet in primiparous cows; it also increased yields of 4% FCM and fat versus the 18.7% CP, untreated diet in primiparous cows. Blood urea N concentrations were greater for high CP diets than for the low CP diet in both parity groups. Rumen acetate: propionate ratios were higher for both high CP diets than for the low CP diet in multiparous cows. Soybean meal enhanced with rumen undegradable protein improved yields of milk and its components in primiparous cows fed low fiber diets, even when high protein diets were fed.     

Protein level for alfalfa and corn silage-based diets: I. Lactational response and milk urea nitrogen

This study was designed to evaluate lactational responses of cows fed corn silage (CS) or alfalfa silage (AS) as primary forage source when the diet was balanced for recommended (RP) or excessive (HP) amounts of rumen degradable protein (RDP) and undegradable protein (RUP) according to the recommendations of the National Research Council (NRC). A second objective was to evaluate different sources of variations in milk urea N (MUN). The total mixed rations included 55% forage on a dry matter (DM) basis as either 14% CS and 41% AS or 14% AS and 41% CS. Diets were offered to 48 multiparous Holstein cows (body weight = 652 kg) that were assigned randomly to treatments arranged as a 2 x 2 factorial in 12 complete blocks based on calving date. Data collected during wk 4 to 12 of lactation were adjusted to those obtained from a pretreatment diet fed during wk 1 to 3. Crude protein (CP) averaged 16.5, 18.0, 16.2, and 17.1% of DM in the AS-RP; AS-HP; CS-RP; and CS-HP diets, respectively. Overall DM intake (DMI) was 1.5 kg/d lower than predicted by NRC (24.6 vs. 26.1 kg/d), but 3.5% fat-corrected milk (FCM) was higher than expected (46.1 vs. 45.0 kg/d). The responses to a reduction in dietary protein were independent of primary forage source, except for milk true protein (TP) percentage. Primary forage source did not influence DMI, 3.5% FCM, TP yield, or MUN. However, compared with the AS-based diets, cows fed CS-based diets produced more milk (49.0 vs. 46.4 kg/d), less fat (3.07% vs. 3.54% and 1500 vs. 1651 g/d), and tended to gain more body weight. There were no benefits to feeding diets above NRC protein recommendations, regardless of forage source. Reducing CP from 17.5 to 16.4% of diet DM did not alter milk yield (47.7 kg/d) or milk TP yield (1293 g/d), but lowered N intake by 65 g/d (700 vs. 635 g/d) and lowered MUN by 1 unit (12.7 vs. 11.7 mg/dL). A positive correlation between MUN and production efficiency (3.5% FCM/DMI) on wk 3 of lactation suggested that body protein mobilization might impact MUN in early lactation. The correlation between MUN and DMI tended to be negative in wk 3, but was positive in wk 6 to 12 of lactation. The same was true for the correlation between MUN and somatic cell score. Regression analysis of the postpeak lactation data of this study indicated that the expected MUN was essentially 12 mg/dL when NRC-predicted RDP and RUP balances were 0 g/d, with a linear deviation of 0.1 and 0.03 mg/dL per 10 g of change in RDP and RUP balance, respectively.     

Lactational response of dairy cows to increased dietary crude protein with added fat.

Thirty-six Holstein cows were assigned to one of three diets containing soybean meal (16% CP), added fat from extruded soybeans (16% CP), and added fat and protein from extruded soybeans plus soybean meal (18% CP) to determine whether feeding additional protein would prevent the depression in milk protein percentages usually experienced when cows are fed additional fat. Total mixed diets containing 25% corn silage, 25% alfalfa hay, and 50% of respective concentrate mixtures were fed individually wk 4 through 16 postpartum; pretreatment (wk 3 postpartum), milk production, and composition data were used as covariates. Milk production (33.0, 35.8, and 34.2 kg/d) was higher for cows fed added fat. Milk protein (2.92, 2.88, and 2.83%) and casein (2.16, 2.13, and 2.09%) tended to decrease for cows fed added fat and did not increase with higher dietary protein. Dry matter intakes (20.9, 20.7, and 19.8 kg/d) and BW were similar for all diets. Supplementing additional CP to a diet containing added fat did not prevent depression in milk protein percentage.