Addition of sodium bicarbonate to rations of pre- and postpartum dairy cows

Sodium bicarbonate was added to complete mixed rations to evaluate the effect of buffer addition on adaptation to high-energy rations by dairy cows in elderly lactation. Forty-five Holstein cows were assigned to one of three treatment groups: control pre- and postpartum; control prepartum, buffer postpartum; and buffer pre- and postpartum. Rations consisted of 85% chopped grass hay: 15% concentrate prepartum and 60% corn silage:40% concentrate postpartum. On day 4 postpartum, cows were switched abruptly to the postpartum ration for 9 wk. Buffered rations contained .6% sodium bicarbonate prepartum and .7% postpartum. Daily dry matter intake as a percent of body weight for cows fed buffer postpartum (3.51%) was greater than for cows fed no buffer (3.04%) of buffer pre- and postpartum (3.14%). Average production of 4% fat-corrected milk was greater for cows fed buffer postpartum and buffer pre- and postpartum (31.9 kg/day and 31.7 kg/day) than for cows fed no buffer (28.9 kg/day). Milk fat tests were not different. Cows fed the buffered rations lost body weight between wk 1 and 9 as compared to a net gain for cows fed no buffer. Cows fed buffers consumed more dry matter during wk 1 than did cows fed no buffer. Samples of rumen fluid, feces, and serum showed few differences that could be attributed to treatments. Compared to controls, cows fed sodium bicarbonate adapted to rations more rapidly postpartum as indicated by increased feed intake during the first 2 wk and by increased milk production during the first 4 wk of the trial.     

The feeding value of extruded corn grain in a corn silage-based ration for high-producing Holstein cows and heifers during mid lactation

The objective of this study was to investigate the feeding value of extruded corn in a corn silage-based ration for high-producing Holstein cows during mid lactation. Sixteen multiparous and 8 primiparous Holstein cows (106 ± 49.7 d in milk; 43.7 ± 5.27 kg of milk/d) were paired based on parity, days in milk, milk production, and body condition score and assigned to 1 of 2 dietary treatments in a randomized block design for 10 wk including a 2-wk adaptation period. Cows were fed a total mixed ration and milked 3 times per day. Diets contained 44% forage (3:1; corn silage:grass silage), 44.7% grain, and either extruded corn (EXC) or finely ground corn (FGC) at 11.3% of ration dry matter. No significant differences were detected in dry matter intake, milk protein yields, fat-corrected milk yields, or body condition score between cows fed FGC and cows fed EXC. Multiparous cows fed EXC produced more milk during wk 3 through 8 with a reduced milk fat content compared with multiparous cows fed FGC. Milk protein content was greater for primiparous cows fed EXC during wk 5 through 8 compared with primiparous cows fed the FGC ration. The major effect of feeding 2.7 kg/d of EXC compared with FGC was an increase in milk production and a reduction in milk fat content for multiparous cows, and an increase in milk protein content for primiparous cows.     

Influence of a novel bm3 corn silage hybrid with floury kernel genetics on lactational performance and feed efficiency of Holstein cows

Dry matter intake, lactation performance, and chewing behavior of multiparous Holstein cows (n = 15) fed diets containing a novel bm3 corn silage hybrid with floury kernel genetics were compared with cows fed diets containing commercially available conventional and bm3 hybrids using a replicated 3 × 3 Latin square design with 28-d periods. Cows were housed in tiestalls, milked 3 times/d, and fed a total mixed ration containing 49.0% (dry matter basis) of (1) a conventional corn silage hybrid (CONV); (2) a brown midrib bm3 hybrid (BMR); or (3) a bm3 hybrid with floury kernel genetics (BMRFL). All diets contained 6.3% hay crop silage and 44.7% concentrate. Dietary nutrient composition averaged 32.7% neutral detergent fiber (NDF) and 26.3 starch (% of dry matter). Data were analyzed by ANOVA using the MIXED procedure in SAS (SAS Institute Inc., Cary, NC). The dry matter intake was greater for cows fed BMR (28.0 kg/d) compared with CONV (26.8 kg/d), whereas dry matter intake for cows fed BMRFL was intermediate (27.6 kg/d). Energy-corrected milk (ECM) yield was greater for cows fed BMR (50.3 kg/d) and BMRFL (51.8 kg/d) compared with CONV (47.2 kg/d). Milk fat yield was higher for cows fed BMRFL (1.87 kg/d) compared with CONV (1.74 kg/d) and BMR (1.80 kg/d). Milk protein yield was greater for cows fed BMR (1.49 kg/d) and BMRFL (1.54 kg/d) compared with CONV (1.36 kg/d). Milk urea-N was reduced for cows fed BMR (11.61 mg/dL) and BMRFL (11.16 mg/dL) compared with CONV (13.60 mg/dL). Feed efficiency (ECM/dry matter intake) was higher for cows fed BMRFL (1.87) compared with CONV (1.76) and BMR (1.79). Milk N efficiency was greatest for cows fed BMRFL (40.4%) followed by BMR (38.1%) and finally CONV (35.3%). Cows fed CONV chewed 5 min more per kilograms of NDF consumed than cows fed either of the BMR hybrids. No differences were observed among diets in apparent total-tract digestibility of NDF (58.1%) or starch (99.3%). Overall lactational performance was enhanced for cows fed diets containing both BMR and BMRFL hybrids versus CONV. In addition, feeding the BMRFL corn silage improved efficiency of component-corrected milk production and milk N efficiency compared with the CONV and BMR silages.     

Production response to corn silage produced from normal, brown midrib, or waxy corn hybrids

The objective was to evaluate the nutrient intake and digestibility and milk production response of lactating dairy cows fed diets based on corn silage produced from 3 different types of corn hybrids. Experimental diets contained 36.4% of the dietary dry matter (DM) from corn silage produced from normal (Agratech 1021, AgraTech Seeds Inc., Atlanta, GA), brown midrib (BMR; Mycogen F2F797, Mycogen Seeds, Indianapolis, IN), or waxy (Master's Choice 590, Master's Choice Hybrids, Ullin, IL) hybrids. Thirty-six multiparous and primiparous Holstein cows (66 ± 22 d in milk, 41 ± 8 kg/d of milk) were used in an 11-wk completely randomized design trial during the fall of 2009. All cows were fed a diet containing normal corn silage during the first 2wk of the trial before being assigned to 1 of 3 treatments for the following 9 wk. Data collected during the first 2 wk were used as a covariate in the statistical analysis. No difference was observed in dry matter intake (DMI) among treatments, which averaged 22.6 kg/d. Milk yield was higher for cows fed BMR (37.6 kg/d) compared with waxy (35.2 kg/d) but was similar to that of cows fed control (36.2 kg/d). Milk fat percentage tended to be lower for cows fed control (3.28%) compared with those fed BMR (3.60%) or waxy (3.55%) corn silage. Milk protein percentage tended to be lower for cows fed control (2.79%) compared with waxy (2.89%) but similar to that of those fed BMR (2.85%). No differences were observed in yield of milk components. Energy-corrected milk (ECM) yield and dairy efficiency (ECM:DMI) did not differ among treatments. Cows fed BMR tended to gain more body weight compared with those fed control and waxy. Results of this trial are consistent with previous reports in which cows fed diets based on corn silage produced from BMR hybrids have higher milk yield compared with those fed other hybrids. Corn silage produced from the waxy hybrid supported a similar yield of ECM because of higher milk components, but milk yield was not improved compared with the control.     

Influence of buffering early lactation rations with sodium bicarbonate and magnesium oxide and subsequent withdrawal or addition effects

Eighty animals (16 first lactation) were assigned alternately at calving to one of four treatments: A) corn silage, B) corn silage + 1.5% sodium bicarbonate and .5% magnesium oxide in the grain mix, C) 50% hay crop silage and 50% corn silage, and D) 50% hay crop silage and corn silage plus 1.5% sodium bicarbonate and .5% magnesium oxide. All rations contained 50% forage and 50% concentrate (dry) fed as a total mixed ration. During the first 8 wk of lactation no differences were detected in mean performance or in weekly patterns for forage programs alone or buffer treatments alone on average daily intake of dry matter, body weight loss, milk yield, or composition. Addition of buffers to hay crop silage and corn silage rations resulted in a milk yield profile with a smaller increase beyond wk 3 postpartum. Cows fed all corn silage rations yielded more milk on the average than cows on hay crop silage and corn silage, regardless of buffer treatments. From wk 9 through 12 of lactation, buffers either were added or withdrawn. Addition or withdrawal of buffers did not alter significantly patterns of milk yield or composition.     

Prepartum grain feeding and subsequent lactation forage program effects on performance of dairy cows in early lactation

One hundred fifty-six Holstein cows were balanced prior to drying off to one of three diets offered during the dry period (dry matter basis): A) forage only (50% corn silage:50% alfalfa silage), B) forage as A plus a standard dairy grain mix (1.73% calcium), and C) same as B except a low calcium grain mix (.35% calcium). Grain feeding started 3 wk prepartum. Cows from each dry treatment were assigned to one of two treatments during the first 21 d postpartum: total mixed ration (dry matter basis); 50% grain:50% corn silage; or 50% grain:25% corn silage:25% alfalfa silage. Dry period feeding program had no effect on postpartum dry matter intake, milk yield, or composition. Prepartum grain feeding resulted in increased body weight gain during the last 3 wk of the dry period. Feeding corn silage postpartum as the sole forage resulted in higher dry matter intakes (15.0 vs. 14.1 kg/d), milk production (31.3 vs. 29.7 kg/d), and less body weight loss (36 vs. 58 kg) during the first 21 d postpartum than feeding a 50% corn silage:50% alfalfa silage mixture. However, differences varied depending on dry cow feeding program. All dry cow treatments resulted in a high incidence of milk fever (11.5, 11.5, and 15.5% for A, B, and C, respectively). Dry cow rations containing as little as 50% alfalfa silage appear to predispose cows to increased incidence of milk fever.     

Effect of feeding silages from corn hybrids selected for leafiness or grain to lactating dairy cattle

Three corn hybrids were harvested as silage and fed to lactating dairy cows to determine performance and digestibility differences between hybrids. Corn hybrids were a grain type, a generic blend, and a leafy type. Starch content of the grain, blend, and leafy silage hybrids was 26.1, 23.8, and 23.5%, respectively. In vitro digestible dry matter of the leafy hybrid silage (69.2%) was higher than the grain (66.8%) or blend (66.7%) hybrid silage. Sixty-two Holstein cows (39 primiparous and 23 multiparous) were fed diets containing (dry matter basis) 40.6% of one of the corn silages, 10.2% alfalfa haylage, 23.5% corn grain, 7.4% whole-fuzzy cotton-seed, 13.8% protein concentrate, and 4.5% vitamin and mineral mix. Cows were assigned to their silage treatment diet 3 d after parturition and remained on the diet until wk 22 of lactation. Dry matter intake, milk yield, and milk components did not differ for cows fed the grain, leafy, or generic blend silage diets for either parity group. Digestibilities of dry matter, organic matter, and neutral detergent fiber, and rate of passage were not different across the silage diets for either parity. Multiparous cows receiving the blend silage diet lost more weight throughout the 22-wk study than did cows on the leafy or grain silage diets. Primiparous cows receiving the blend silage diet spent more time eating than cows on either the grain or leafy silage diet. Time spent chewing did not differ among hybrids. Corn hybrid at 40% of dietary dry matter as silage did not have a major impact on dairy cattle performance in this trial.     

No Associative Effects Between Corn and Haycrop Silages Fed to Lactating Dairy Cows

Four first-lactation Holstein cows were used 65 to 177 days postpartum in a 4 × 4 Latin square trial to evaluate possible associative feeding effects between corn and haycrop silages. Nutrient digestibility and nitrogen and energy balances were studied. Diets were concentrate mixture, urea-treated corn silage, and early-cut, wilted haycrop silage in dry matter ratios of 55:45:0, 55:30:15, 55:15:30, and 55:0:45. Rations were offered just below energy balance in each 28-day period. Ration components were fed separately, concurrently, and twice daily. Crude protein in concentrate, corn silage, and hay crop silage dry matter was 16.9, 11.1, and 12.5%. Milk yield (18 to 19 kg) and ration dry matter intake (2.61% body weight) were not significantly different among diets. Apparent digestibility of gross energy, dry matter, protein, and fiber was not different among diets, but fat was more digestible in corn silage. Partition of ingested energy and nitrogen was not affected by treatments except that urine nitrogen was higher in corn silage. No associative feeding effects were significant. The two silages were equivalent in supporting milk production when fed in equal dry matter amounts.     

Whole rolled sunflower seeds with or without additional limestone in lactating dairy cattle rations

Thirty lactating Holstein cows were in a continuous trial from 21 to 120 days postpartum to evaluate diets containing whole, rolled sunflower seeds with or without additional limestone. Cows were fed individually total mixed rations of (dry matter) 47% corn silage, 9% alfalfa hay, and 44% concentrate. Concentrates were corn and soybean meal (control); corn, soybean meal, and 22% sunflower seeds; or corn, soybean meal, and sunflower seeds plus 3.5% additional limestone. Milk yield (32.2, 32.0, and 32.8 kg/day) was similar among rations. Yield of 4% fat-corrected milk was lower for cows fed sunflower seeds without additional limestone (30.2, 28.1, and 30.2 kg/day) because of lower milk fat percentages (3.57, 3.19, and 3.51). Milk protein percentage tended to be lower for cows fed sunflower seeds with additional limestone (3.01, 2.97, and 2.90). Milk, flavor score was acceptable but tended to be lower for milk from cows fed sunflower seeds with additional limestone (8.4, 8.5, and 7.9). Milk fat from cows fed sunflower seed rations contained less carbon-14:0, 16:0, and 16:1 fatty acids but more carbon-18:0. Dry matter intakes were 21.0, 18.4, and 20.0 kg/day. Dry matter digestibilities, body weight changes, and ruminal volatile fatty acid concentrations were similar among treatments. Total cholesterol in blood serum was elevated in cows fed sunflower seed rations. Insoluble salts of fatty acids were increased in ruminal fluid dry matter from cows fed sunflower seeds but were not increased further by additional limestone. Concentrations of nonesterified carbon-18:1 fatty acids in ruminal fluid dry matter were lower for cows fed sunflower seeds with additional limestone.     

Milk production and composition from cows fed wet corn distillers grains

Twelve lactating Holstein cows were utilized in a repeated switchback design to evaluate milk production and milk fat composition responses to wet corn distillers grains. Total mixed diets consisted of 31.4% corn silage, 18.4% alfalfa hay, and either 50.2% of a concentrate mix that contained mostly corn and soybean meal or 19.4% of a concentrate mix that contained mostly corn and 31.2% wet corn distillers grains. The first 4 wk of each 6-wk period were for adaptation to diets; data were collected during wk 5 and 6 of each period. Although dry matter intake (22.1 vs. 19.7 kg/d) was lower when cows were fed the wet corn distillers grains diet, milk production (30.7 vs. 30.8 kg/d) was similar for cows fed both diets. Milk fat (3.60 vs. 3.85%) was slightly higher, and protein (3.06 vs. 2.84%) was lower, when cows were fed the wet corn distillers grains diet. Milk fat from cows fed wet corn distillers grains contained lower concentrations of saturated fatty acids and higher concentrations of long-chain and unsaturated fatty acids. The feeding of wet corn distillers grains increased the proportion of unsaturated fatty acids in milk fat without changing milk production.     

Evaluation of wet corn gluten feed in diets for lactating dairy cows.

Two experiments were conducted to evaluate responses of primiparous and multiparous Holstein cows to diets containing wet corn gluten feed (WCGF). In both experiments, WCGF replaced a mix of alfalfa hay, corn silage, and corn grain. In experiment 1, 32 primiparous Holstein cows (four pens with eight cows/pen) were used in two 2 x 2 Latin squares with 28-d periods. Cows were housed in free stalls and fed diets containing 0 or 20% WCGF dry matter (DM) basis. Cows fed WCGF consumed more DM and produced more energy-corrected milk (ECM) than controls. Production efficiency (ECM/DM intake) was not affected, but yield of milk components was improved by WCGF. In experiment 2, 24 multiparous Holstein cows were used in six 4 x 4 Latin squares with 28-d periods to determine the optimal dietary inclusion rate for WCGF. Cows were housed in a tie-stall barn and fed a total mixed ration twice daily. Treatments were 0, 20, 27.5, and 35% WCGF (DM basis). Cows fed WCGF produced more ECM than controls, but ECM did not differ among cows fed WCGF diets. Cows fed 20 and 27.5% WCGF consumed more DM as a percentage of body weight than those fed either 0 or 35% WCGF. Cows fed WCGF produced ECM more efficiently than controls. Percent milk fat was lower, but fat yield was not different when WCGF was added to diets. Milk protein and lactose yields were higher when WCGF was fed. Plasma glucose, alpha-amino N, and triglyceride concentrations were similar among diets in both experiments, but plasma urea N was higher for cows fed WCGF in experiment 2.     

Influence of dietary protein concentration on milk production by dairy cattle during early lactation

In a 3 X 2 factorial experiment 75 Holstein cows in first, second, or third lactation were fed rations containing either 12.2% or 16.2% crude protein in total ration dry matter. On the average, 26% of dry matter intake was from corn silage, 22% from alfalfa-grass hay, and 52% from a grain mix. Protein was controlled by feeding a 13.7% crude protein grain mix with 1.4% urea for the 12% ration and a 19.8% crude protein grain mix with natural protein for the 16% ration. Average daily milk production (kg/day) for wk 2 through 12 of lactation for 12% and 16% rations by lactations were: first, 21.6 and 21.9; second, 25.7 and 31.5; and third, 27.5 and 34.0. Dry matter intakes by lactations were .42, 1.18, and 2.05 kg/day higher for cows fed the high protein compared to low protein rations. Milk composition was not influenced by protein treatment. The markedly different response to protein supplementation in milk production between heifers in first lactation and more mature cows is unexplained.     

Corn silage hybrid effects on intake, digestion, and milk production by dairy cows

Three corn hybrids harvested as whole-plant silage were evaluated in three separate feeding trials with lactating dairy cows. In trial 1, 24 multiparous Holstein cows were used in a replicated 4 x 4 Latin square with 28-d periods. Treatments were conventional (Pioneer 3563) and leafy (Mycogen TMF 106) corn silage hybrids, each planted at low (59,000 plants/ha) and high (79,000 plants/ha) plant populations. There were no milk production differences between treatments. Total-tract digestibility of dietary starch was higher for leafy compared with conventional corn hybrids. In trial 2, 26 multiparous Holstein cows were assigned randomly to diets containing either conventional (48% forage diet) or brown-midrib (60% forage diet) corn silage in a crossover design with 8-wk periods. Milk yield was lower, but milk fat percentage and yield were higher, for the high-forage diet containing brown-midrib corn silage. In trial 3, 24 multiparous Holstein cows were used in a replicated 4 x 4 Latin square with 28-d periods. Treatments were corn silage at two concentrations of neutral detergent fiber (Garst 8751, 39.2% NDF; Cargill 3677, 32.8% NDF) each fed in normal- (53% of dry matter) and high- (61 to 67% of dry matter) forage diets. Milk production was not different between corn hybrids. Increased concentrate supplementation increased DMI and milk production. There were minimal benefits to the feeding of leafy or low-fiber corn silage hybrids. Feeding brown-midrib corn silage in a high-forage diet increased milk fat percentage and yield compared with conventional corn silage fed in a normal-forage diet.     

Addition of sodium bicarbonate to rations of postpartum dairy cows: physiological and metabolic effects

Sodium bicarbonate was added to complete mixed rations to characterize physiological, metabolic, and ruminal changes immediately postpartum when dairy cows are switched abruptly from a low energy ration prepartum to a high energy ration postpartum. Twelve Holstein cows were paired and assigned randomly to either a control or buffered ration containing .8% sodium bicarbonate. Rations consisted of 50% corn silage:50% concentrate. All All cows were fed a similar dry cow ration for a minimum of 7 days prepartum and experimental rations for 2 wk beginning at parturition. Blood, feces, and urine were sampled on days 1, 2, 4, 7, 10, and 14 postpartum. Rumen fluid was sampled on days 7 and 14. Dry matter intake and milk production were 2.75% of body weight and 30.3 kg/day for cows fed buffer and 2.49% and 27.6 kg/day for cows fed control. Higher partial pressure of carbon dioxide and base excess in blood in cows fed buffer existed on days 2 and 4 postpartum than for cows fed the control ration. Cows fed buffer had higher concentrations of ruminal ammonia than cows fed control. This difference was less pronounced in blood urea nitrogen and urinary ammonia. Urine pH was higher for cows fed buffer than for control. Addition of sodium bicarbonate improved the acid-base status after abrupt change of ration and may be associated with increased dry matter intake and improved ration adaptation. Concentrations of most minerals and metabolites in blood serum did not differ between rations.     

Comparison of full-fat corn germ, whole cottonseed, and tallow as fat sources for lactating dairy cattle

Twenty-four multiparous Holstein cows (124 ± 39 d in milk; 682 ± 72 kg of body weight) were used in 6 simultaneous 4 × 4 Latin squares to evaluate full-fat corn germ as a fat source for lactating dairy cows. Experimental diets were a control (containing 28% ground corn, 23% alfalfa hay, 19% wet corn gluten feed, and 10% corn silage, dry matter basis), and 3 diets with either whole cottonseed (WCS), tallow (TAL), or full-fat corn germ (FFCG) added to provide 1.6% supplemental fat. Cows were fed twice daily for ad libitum intake. Dry matter intake, milk yield, and energy-corrected milk did not differ among diets. Efficiency of milk production (energy-corrected milk/dry matter intake) was greater for cows fed WCS than for cows fed the control, TAL, or FFCG. Milk fat percentage from cows fed FFCG was less than that of cows fed WCS or the control, but was similar to that of cows fed TAL. Milk protein percentage was less for cows fed FFCG than for those fed the control. Total saturated fatty acids were less in milk from cows fed fat sources, and cows fed WCS and TAL had greater saturated fatty acids in milk than did cows fed FFCG. Unsaturated fatty acids were greater in milk from cows fed FFCG than in milk from cows fed the control, WCS, or TAL. The cis-9, trans-11 conjugated linoleic acid content was greater in milk from cows fed WCS, TAL, and FFCG than from cows fed the control, and it was greater in milk from cows fed FFCG than in milk from cows fed WCS or TAL. These results indicate that FFCG can be used effectively as a fat source in diets for lactating dairy cattle.     

Maximizing profit on New England organic dairy farms: an economic comparison of 4 total mixed rations for organic Holsteins and Jerseys

The objective of these experiments was to compare 4 total mixed rations fed to USDA-certified organic dairy cows in New England. Forty-eight Jersey cows from the University of New Hampshire (UNH) and 64 Holstein cows from the University of Maine (UMaine) were assigned to a 2 × 2 factorial arrangement of treatments testing the main effects of corn silage versus grass silage as the forage base and commodity concentrates versus a complete pelleted concentrate mixture. Treatment diets were fed as a total mixed ration for 8 wk during the winter and spring months of 2007, 2008, and 2009. Milk yield, component, and quality data were recorded and used to calculate the value of the milk produced for each cow. The dry matter intake (DMI) was recorded and used to calculate the average cost per cow per day of each diet. Income over feed costs were calculated for each diet using milk value and feed cost data. Feed cost and income over feed cost data were resampled using bootstrap methodology to examine potential patterns. Milk yield, milk fat and true protein concentrations, and SCC were similar among treatments. Cows at UNH fed corn silage tended to have higher DMI and lower milk urea nitrogen than did cows fed grass silage, whereas cows fed pellets had higher DMI than cows fed commodities. Cows at UNH fed commodities tended to have higher body condition scores than those fed pellets. Cows at UMaine fed commodities tended to have higher DMI than did cows fed pellets, and cows fed corn silage had lower milk urea nitrogen than did cows fed grass silage. Body weights and body condition scores were not different for cows at UMaine. Feed costs were significantly higher for corn silage diets and diets at UNH containing pellets, but not at UMaine. The calculated value of the milk and income over feed costs did not differ among treatments at either university. Bootstrap replications indicated that the corn silage with commodities diet generally had the highest feed cost at both UNH and UMaine, whereas grass silage diets containing commodities generally had the lowest cost. In contrast, the grass silage with commodities diets had the highest income over feed cost in the majority of the replications at both UNH and UMaine replications, whereas the corn silage with commodities diets had the lowest rank. Similar results were observed when forage prices were increased or decreased by 5, 10, and 25% above or below the actual feed price. Feeding a grass silage-based diet supplemented with commodity concentrates may have an economic advantage for dairy producers in New England operating under an organic system of production.     

The effect of dry period length and postpartum level of concentrate on milk production,energy balance,and plasma metabolites of dairy cows across the dry period and in early lactation

Shortening or omitting the dry period (DP) improves energy balance (EB) in early lactation because of a reduction in milk yield. Lower milk yield results in lower energy demands and requires less energy intake. The aim of this study was to evaluate the effects of DP length and concentrate level postpartum on milk yield, feed intake, EB, and plasma metabolites between wk ?4 and 7 relative to calving of cows of second parity or higher. Holstein-Friesian dairy cows (n = 123) were assigned randomly to 1 of 2 DP lengths: 0-d DP (n = 81) or 30-d DP (n = 42). Prepartum, cows with a 0-d DP received a lactation ration based on grass silage and corn silage (6.4 MJ of net energy for lactation/kg of dry matter). Cows with a 30-d DP received a dry cow ration based on grass silage, corn silage, and straw (5.4 MJ of net energy for lactation/kg of dry matter). Postpartum, all cows received the same basal lactation ration as provided to lactating cows prepartum. Cows with a 0-d DP were fed a low level of concentrate up to 6.7 kg/d based on the requirement for their expected milk yield (0-d DP-L; n = 40) or the standard level of concentrate up to 8.5 kg/d (0-d DP-S; n = 41), which was equal to the concentrate level for cows with a 30-d DP (30-d DP-S; n = 42) based on requirements for their expected milk yield. Prepartum dry matter intake, concentrate intake, basal ration intake, energy intake, plasma β-hydroxybutyrate (BHB), and insulin concentrations were greater and plasma free fatty acids (FFA) and glucose concentrations were lower, but EB was not different in cows with a 0-d DP compared with cows with a 30-d DP. During wk 1 to 3 postpartum, milk fat yield and plasma BHB concentration were lower and dry matter intake and concentrate intake were greater in cows with a 0-d DP compared with cows with a 30-d DP. During wk 4 to 7 postpartum, fat- and protein-corrected milk (FPCM), lactose content, and lactose and fat yield were lower in 0-d DP-L or 0-d DP-S cows compared with 30-d DP-S cows. Basal ration intake, EB, body weight, plasma glucose, and insulin and insulin-like growth factor-1 concentrations were greater and plasma FFA and BHB concentrations were lower in 0-d DP-L and 0-d DP-S cows compared with 30-d DP-S cows. Concentrate and energy intake were lower in 0-d DP-L cows than in 0-d DP-S or 30-d DP-S cows. Milk yield and concentrations of plasma metabolites did not differ in wk 4 to 7, although EB was lower in wk 6 and 7 postpartum in 0-d DP-L cows than in 0-d DP-S cows. In conclusion, a 0-d DP reduced milk yield and improved EB and metabolic status of cows in early lactation compared with a 30-d DP. Reducing the postpartum level of concentrate of cows with a 0-d DP did not affect fat- and protein-corrected milk yield or plasma FFA and BHB concentrations in early lactation but did reduce EB in wk 6 and 7 postpartum.     

Effect of rumen protein degradability on milk yield of dairy cows in early lactation

Twenty-four mature Holstein cows were fed diets of 40% corn silage and 60% concentrate (dry matter) beginning at parturition through wk 16 of lactation. A control concentrate (corn, soybean meal, and barley) was fed through wk 4 followed by assignment of cows to either a concentrate of low or high rumen protein degradability. In situ trials with two fistulated cows fed similar diets yielded rumen protein degradabilities of 78.5, 70.3, 69.9, 67.3, 49.1, and 36.5% for barley, corn, corn gluten feed, soybean meal, brewer's grains, and cottonseed meal. The low degradability concentrate (corn, cottonseed meal, brewer's grains, and corn gluten feed) had an estimated rumen protein degradation of 52.9% and a total ration crude protein of 14.3%. The high degradability concentrate containing corn, barley, and soybean meal was 72.8% rumen degradable, and total ration protein for this treatment was 14.5%. Dry matter intakes were 21.0 and 22.0 kg/day for the low and high degradability diets. Milk yield, fat percent, and fat-corrected milk were not affected by treatment. Milk protein percent and protein yield decreased from 3.00 to 2.84% and 1.07 to .99 kg/day in the high and low degradability diets. Efficacy of use of degradability as a criterion for feed formulation is questioned until understanding of both feed protein breakdown and microbial synthesis is greater.     

Performance of lactating dairy cows fed whole cottonseed coated with gelatinized cornstarch.

The handling characteristics of whole cottonseed are improved by coating with gelatinized cornstarch, but limited information is available on the effects of feeding the coated cottonseed to lactating dairy cows. Thirty-six lactating Jersey cows were used in a crossover design trial with 4-wk experimental periods to evaluate the influence of coating whole cottonseed with 2.5% gelatinized cornstarch on dry matter intake, milk yield, and composition. Cows were fed diets containing 10.2% alfalfa-orchardgrass hay, 45.2% corn silage, 15.0% coated or uncoated whole cottonseed, and 29.6% concentrate for ad libitum consumption. Coating whole cottonseed with gelatinized cornstarch tended to reduce dry matter intake, which averaged 16.2 and 15.9 kg/d for uncoated and coated cottonseed, respectively. Milk yield and composition were similar for uncoated and coated cottonseed. The yield of energy-corrected milk per unit of dry matter consumed was greater with coated cottonseed. Cows fed coated cottonseed gained body weight, but cows fed uncoated cottonseed lost weight. Concentrations of plasma urea were similar among treatments; however, NEFA concentrations were lower for cows fed coated whole cottonseed. Results of this trial indicate that coating whole cottonseed with 2.5% gelatinized cornstarch does not alter its feeding value for lactating dairy cows.     

Influence of formaldehyde-treated soybean meal on milk production

Forty-eight Holstein cows were fed one of four diets containing 12.5% crude protein (negative control); 15.5% crude protein with untreated soybean meal; 15.5% crude protein with formaldehyde (.3%)-treated soybean meal; or 18% crude protein (positive control). Diets were 60% concentrate, 22% corn silage, 14% alfalfa hay, and 4% beet pulp (dry matter). Data were collected during the first 200 d of lactation. Dry matter intake, milk, and milk component yields did not differ among cows fed the untreated soybean meal, treated soybean meal, and positive control diets. Cows fed negative control diet consumed less dry matter and produced less milk than cows fed the other diets. Milk protein yield was lower for cows fed the negative control diet compared with the other diets. Nonprotein nitrogen content of milk increased as dietary protein increased.