Solids-corrected Milk Yield Research Articles

Effects of sequential treatments with eprinomectin on performance and grazing behaviour in dairy cattle under daily-paddock stocking management

To evaluate the effect of gastrointestinal parasites on grazing behaviour, herbage intake and milk production in spring calving dairy cows, 12 naturally infected control cows were compared with 12 similar animals treated on three occasions (June, July and September) with eprinomectin. The cows were blocked according to calving date, parity, live weight and milk yield during week 2 after turnout and then allocated to the treatments. The grazing area was sub-divided into two sets of 12 replicated paddocks of equivalent size and topography. Pairs of either control or treated animals were randomly assigned to graze each paddock over the duration of the study. Within each plot, the pair of cows grazed a series of 1-day paddocks, of areas calculated to provide 72 kg of herbage dry matter measured to ground level. Faecal samples were collected from each cow in April, prior to allocation, and every 28 days thereafter. Samples were submitted for counts of nematode eggs (sensitivity 1 epg) and the presence of Dictyocaulus viviparus larvae. Additional faecal samples were taken on each occasion for culture and nematode identification. Pasture samples for direct larval counts were collected at the same time as faecal sampling. Behaviour measurements on all cows were made during three periods, once before the first treatment with eprinomectin and thence after the 2nd and 3rd treatments. During each behaviour measurement period, grazing and ruminating behaviour were recorded over two 24-h periods and measurements of components of short-term intake rate were made during a morning and a late afternoon grazing meal. Milk yield was recorded daily and milk quality was recorded weekly. Live weight and body condition score were recorded on the day of allocation, the day of initial treatment and thereafter at weekly intervals until the end of the trial. The parasitological results showed low levels of faecal egg output throughout the study with group arithmetic means ranging from 0 to 6.8 epg. Faecal culture yielded predominantly larvae of the genus Ostertagia, but the following genera were also identified: Cooperia, Oesophagostomum and Trichostrongylus. Pasture larval levels were also low with peak values of 135 and 58 L3/kg DM herbage (7 August) in the paddocks grazed by the control and treated cattle, respectively. Thereafter, larval counts on paddocks grazed by treated cows declined to undetectable levels by October, while control paddocks remained at approximately 40 L3/kg DM. There was no effect of treatment on components of grazing or ruminating behaviour recorded over 24 h or on short-term intake rates. There were significant differences between components of short-term intake rates measured during the morning and afternoon grazing meals. The overall milk yield response to treatment with eprinomectin was +1.68 kg/day solids-corrected milk (SCM) ( P = 0.026). The overall response included significant ( P < 0.050) increases in mean daily SCM yield following each of the three treatments, indicating a positive response to repeated treatments at several different stages of lactation. There were no significant differences in the overall percentages of fat, protein or lactose between control and treated groups. The differences in live weight were not significant, although there was a consistent pattern throughout for the treated cows to be heavier than the controls.

Impact of eprinomectin on grazing behaviour and performance in dairy cattle with sub-clinical gastrointestinal nematode infections under continuous stocking management

Forty spring-calving cows and heifers (20 of each) were allowed to acquire infection with gastrointestinal (GI) nematodes naturally during grazing. The control group (10 cows and 10 heifers) were compared with 20 similar animals treated with eprinomectin in order to evaluate the effect of GI nematodes on grazing behaviour, milk production, body condition score and live weight. The animals were paired according to parity and milk yield during the week prior to treatment, then within replicate pair randomly allocated to a different treatment group. The grazing area was sub-divided into 20 replicated paddocks of equivalent size and topography. Grazing pairs of either control or treated animals were randomly assigned to each paddock over the duration of the study (one pair per paddock). Grazing behaviour was recorded for both groups over a 10-day period commencing 4 days after treatment with eprinomectin. Milk yield was recorded daily and milk quality was recorded weekly. Live weight and body condition score were recorded on the day of allocation, the day of initial treatment and thereafter at weekly intervals until the end of the 4-week trial. Faecal samples were collected from each animal prior to, and after, allocation and submitted for counts of nematode eggs. Additional faecal samples were taken at the end of the study for culture and nematode identification. Individual faecal samples were also analysed for residual digestibility. Pasture samples for nematode larval counts were taken at the same time as faecal sampling. The parasitological results showed low levels of faecal nematode egg output throughout the study, with the heifers having higher counts than the cows. Faecal culture yielded species of Ostertagia, Cooperia, and Trichostrongylus. Pasture larval levels were very low throughout with no value exceeding 68 larvae/kg dry matter (DM) of herbage. There were significant ( P < 0.05) effects of treatment on grazing time, eating time, total bites, total grazing jaw movements (TGJM), idling time and mean meal duration. Treated cows and heifers grazed for 47 and 50 min longer per day, respectively, than controls ( P = 0.016). Mean meal duration was extended as a result of anthelmintic treatment by 11 and 38 min, in cows and heifers, respectively ( P = 0.012). There were no significant ( P > 0.05) treatment effects on ruminating time or residual faecal digestibility, but idling time was significantly reduced in both treated cows and heifers, by 50 and 110 min, respectively ( P = 0.010). In the treated cattle, there was an increase in solids-corrected milk yield compared with the control cattle, which was significant ( P < 0.05) in weeks 2 and 3 after treatment. The response was particularly marked in heifers, where the difference in yield between treated and controls was up to 2.35 kg/day. The differences in live weight gain and condition score over 28 days post-treatment were significant ( P < 0.05) in both cows and heifers, in favour of the treated animals.

The effect of grass cultivars differing in heading date and ploidy on the performance and dry matter intake of spring calving dairy cows at pasture

The system of milk production in Ireland is dependent on the efficient utilisation of grazed grass. Therefore the use of grass cultivars with different heading dates may have a large effect on dairy cow performance. The objective of this study was to determine the effect of grass cultivars differing in heading date and grass ploidy on milk production and grass dry matter intake (GDMI) of spring calving dairy cows. The study took place over two years. Seventy-two spring calving dairy cows in Year 1 and 80 in Year 2 were blocked into groups of four and were assigned randomly to one of four grass cultivar treatments. The grass cultivars differed in heading date (intermediate or late) and grass ploidy (diploid or tetraploid). The grazing season began in April 12 (Year 1) and April 25 (Year 2) and lasted until the end of September in both years. A total concentrate DM input of 248 kg and 45 kg·cow -1 was offered to the herds in Year 1 and in Year 2, respectively. All concentrate was of- fered during the first 3 grazing rotations. Rotation had a significant effect (P < 0.001) on all milk pro- duction parameters in both years. In Year 1, late heading cultivars significantly (P < 0.05) increased milk yield, solids corrected milk yield (SCM), fat, protein and lactose yield. There was a significant interaction (P < 0.05) between heading date and grass ploidy for lactose yield and fat concentration. In Year 2, late heading cultivars had also increased milk yield (P < 0.01), lactose yield (P < 0.05), SCM (P < 0.05), protein yield (P < 0.001) and protein concentration (P < 0.05). In Year 1, the GDMI was higher (P < 0.001) for cows grazing the late heading cultivars. It is concluded that later heading grass cultivars have a beneficial effect on the milk production performance of spring calving dairy cows.

Effects of Corn Grain Conservation Method on Feeding Behavior and Productivity of Lactating Dairy Cows at Two Dietary Starch Concentrations

Effects of conservation method of corn grain and dietary starch concentration on dry matter intake (DMI) and productivity of lactating dairy cows were evaluated. Eight ruminally and duodenally cannulated Holstein cows (55±15.9 d in milk; mean±SD) were used in a duplicated 4×4 Latin square design with a 2×2 factorial arrangement of treatments. Experimental diets contained either ground high-moisture corn (HM) or dry ground corn (DG) at two dietary starch concentrations (32 vs 21%). Mean particle size and dry matter (DM) concentration of corn grain were 1863μm and 63.2%, and 885μm and 89.7%, for HM and DG, respectively. DMI was lower for HM compared to DG treatment in high-starch diets (20.8 vs 22.5kg/d), but similar for the HM and DG treatments in low-starch diets (19.7 vs 19.6kg/d). This reduction in DMI is attributed to smaller meal size for HM compared to DG in high-starch diets (1.9 vs 2.3kg of DM for high-starch diets; 2.1 vs 2.0kg of DM for low-starch diets). Faster starch fermentation for HM in high-starch diets might result in satiety with smaller meal size. Milk yield was greater when cows were fed high-starch diets compared to low-starch diets (38.6 vs 33.9kg/d) regardless of corn grain treatment. High-starch diets increased solids-corrected milk yield by 3.3kg (35.2 vs 31.9kg/d) compared to low-starch diets for cows fed DG, but did not increase for cows fed HM. This was because of a lower milk fat concentration for cows fed HM in high-starch diets. Reducing ruminal starch fermentation by substituting DG for HM can increase the productivity of lactating cows fed high-starch diets.

Effects of Corn Particle Size and Source on Performance of Lactating Cows Fed Direct-Cut Grass-Legume Forage

We conducted two experiments to evaluate the effects of corn supplementation, source of corn, and corn particle size on performance and nutrient utilization of lactating dairy cows. In experiment 1, treatments were 1) direct-cut grass-legume forage without supplement, 2) direct-cut forage plus 10kg DM of ground dry shelled corn-based concentrate, and 3) direct-cut forage plus 10kg DM of coarsely ground high moisture ear corn-based concentrate. In experiment 2, treatments were 1) direct-cut grass-legume forage plus 10kg DM of ground dry shelled corn-based concentrate, 2) direct-cut forage plus 10kg DM of coarsely ground high moisture ear corn-based concentrate, and 3) direct-cut forage plus 10kg of DM finely ground high moisture ear corn-based concentrate. Both experiments were designed as 3 x 3 Latin squares replicated three times. In experiment 1, yields of milk and milk protein increased with concentrate supplementation, but were not affected by source of corn. Solids-corrected milk yield tended to increase with grain supplementation. Dry matter intake increased with concentrate supplementation, but was not affected by source of corn or corn particle size. Corn supplements decreased ruminal pH and acetate to propionate ratio and increased ruminal propionate concentration. Grain supplements reduced ruminal ammonia concentration,6 increased concentration of urine allantoin, and increased the urinary allantoin to creatinine ratio. In the second study, fine grinding of high moisture corn reduced fecal starch plus free glucose levels and tended to increase its apparent digestibility. In both experiments, starch plus free glucose intake was higher on the diets with dry corn, but its utilization was not affected by source of corn.

Effects of Brown Midrib 3 Mutation in Corn Silage on Productivity of Dairy Cows Fed Two Concentrations of Dietary Neutral Detergent Fiber: 1. Feeding Behavior and Nutrient Utilization

The effects of digestibility of corn silage neutral detergent fiber (NDF) and dietary NDF content on feeding behavior, dry matter intake (DMI), and energy utilization were evaluated with eight multiparous high producing dairy cows in a duplicated 4 × 4 Latin square design with 21-d periods. Experimental diets contained corn silage from a brown midrib (bm3) hybrid or its isogenic normal control at two concentrations of dietary NDF (29 and 38%). Both low NDF diets and bm3 corn silage treatments increased DMI and milk yield. However, an interaction between corn silage treatment and dietary NDF content was observed for meal size and for interval between meals, implying that different mechanisms regulating DMI dominate depending on the fermentation characteristics of diets. The bm3 treatment depressed milk fat concentration when fed in a low NDF diet. The bm3 corn silage increased solids-corrected milk yield, but did not affect daily body weight gain compared with control, whereas low NDF diets increased daily body weight gain, but did not affect solids-corrected milk yield compared to high NDF diets. Both bm3 treatments and low NDF diets reduced ruminal pH, but low NDF treatments increased fluctuation of ruminal pH and bm3 treatments did not. Feeding bm3 corn silage increased the energy utilized for milk production, possibly because of a consistent supply of metabolic fuels from the rumen. The beneficial effects of bm3 corn silage on productivity of lactating cows were greater for the cows fed a high NDF diet.

Dietary Interaction of Cane Molasses with Source of Roughage: Intake and Lactation Effects

Effects of cane molasses at 0, 4, and 8% of DM in complete mixed diets were evaluated when molasses was fed to lactating dairy cows with cottonseed hulls, alfalfa haylage, or both combined. Thirty-six mature Holstein cows from mid to late lactation were used in a partially balanced incomplete block design with three 28-d periods. Variables measured were DM intake, milk yield, and composition. With cottonseed hull diets (30% of DM), molasses improved milk yield, milk fat percentage, solids-corrected milk, and feed efficiency. Dry matter intake was not affected by molasses. With alfalfa haylage diets (35% of DM), 8% molasses depressed actual milk yield and solids-corrected milk, DM intake, milk fat percentage, milk protein percentage, and feed efficiency. Milk fat percentage was increased with 4% molasses. With 65% alfalfa haylage diets, most variables measured were unaffected by molasses; however, with 8% molasses, DM intake increased and milk protein percentage decreased. In diets with both roughages combined, molasses did not affect any variable measured; however, these diets gave highest solids-corrected milk yields. Results show clearly that molasses effects depend on percentage molasses and type and amount of roughage in the diet.

COMPARISON OF WILTED-ALFALFA SILAGE AND ALFALFA HAY PRESERVED WITH PROPIONIC ACID IN CORN-SILAGE-BASED DIETS FOR MILKING COWS

Thirty cows (9 uniparous and 21 multiparous) were fed three diets during weeks 5–16 of lactation. The dietary ingredients were adjusted weekly to reflect their oven dry matter (DM). The control diet was a low-fiber diet containing urea-treated corn silage (UCS), well-dried alfalfa hay and buffered concentrate (525:125:350 DM basis). The two test diets contained corn silage and either wilted-alfalfa silage (WAS) or alfalfa hay treated with propionic acid (PAH) and concentrate (300:300:400 DM basis). For the three blended diets, acid detergent fiber (169, 195 and 212 g kg−1 DM) and digestible energy (12.73, 12.50 and 12.25 MJ kg−1 DM) were different (P &lt; 0.05). The crude protein content of the WAS diet was higher (P &lt; 0.05) than that of the PAH diet (164 vs. 154 g kg−1 DM). Average DM intakes (21.8, 22.5 and 21.2 kg d−1) and solids-corrected milk yields (26.9, 27.9 and 26.6 kg d−1) were similar for the three treatments. Also there was no treatment effect (P &gt; 0.05) on milk composition and acetate/propionate ratios of rumen fluid. Thus WAS and PAH diets supported similar production and equalled the low fiber control diet. Key words: Lactation, urea, corn silage, alfalfa, wilted silage, propionic acid treatment.

FEEDING VALUE OF WET CORN GLUTEN FEED FOR LACTATING DAIRY COWS

In two trials 57 and 44 Holstein cows were used to determine the effect of feeding wet corn gluten feed (CGF) on total dry matter (DM) intake and milk production. Treatments compared were: Trial I, control vs. wet CGF at either 18.6 or 37.1% of ration DM; Trial II, control vs. dried or wet CGF each at 26% of ration DM. Within each treatment in Trial II, cows were balanced to receive sodium bicarbonate in either the first or second half of the 10-wk experimental period. Total mixed rations were offered ad libitum. In Trial I the multiparous cows fed either level of CGF, consumed less DM and produced less actual and solids-corrected milk (SCM) than did those fed the control diet. Differences across treatments were greater in the first 4 wk. Primiparous cows showed no (P &gt; 0.05) treatment effects. In Trial II parities were similar in response to treatment. Sodium bicarbonate did not (P &gt; 0.05) affect performance. Milk yield was lower (P &lt; 0.05) on wet CGF than on the control diet but fat- and solids-corrected milk yield, DM intake and body weight change were similar, and fat percent in milk greater for wet CGF. Feeding dried CGF resulted in greater (P &lt; 0.05) DM intake, SCM, percent protein in milk and body weight changes than either control or wet CGF. Wet CGF was lower (P &lt; 0.05) in insoluble N and higher in soluble NPN than dried CGF. We concluded that dried CGF is superior to wet CGF for lactating cows but that wet CGF should be considered for feeding when cost/benefit analysis suggests an economic advantage. Key words: Wet corn gluten feed, lactation, dairy cows, protein solubility

EFFECT OF FEEDING SOYBEAN MEAL PROTECTED WITH SODIUM HYDROXIDE, FRESH BLOOD, OR FISH HYDROLYSATE TO GROWING CALVES AND LACTATING DAIRY COWS

Soybean meal (SBM) protected from degradation in the rumen by NaOH, fresh blood (BL) or fish hydrolysate (FH) was evaluated in a digestibility and nitrogen (N) balance trial using weaned male Holstein calves and in a lactation trial (FH was not included) with multiparous high-yielding Holstein cows. N digestibility increased (P &lt; 0.05) by inclusion of NaOH-treated SBM in the diet. N retention by calves increased (P &lt; 0.05) with NaOH or BL treatment. DM intakes and milk composition in the lactation trial were not different across treatments. Milk yield, fat-corrected milk and solids-corrected milk yields and efficiency of protein utilization by cows fed NaOH-treated SBM diet were higher (P &lt; 0.05) than by cows fed untreated SBM diet. These observations suggest that inclusion of NaOH- or BL-treated SBM results in improved protein utilization by young growing calves. NaOH treatment of SBM also results in production of more milk in high-yielding cows during early lactation. Key words: Soybean meal, sodium hydroxide, blood, fish hydrolysate, protected protein, calves, dairy cows

Effect of Dietary Protein Degradability on Cows in Early Lactation

Five completely mixed isocaloric diets were formulated with ratio of 50:50 roughage: concentrate (dry matter) to vary in protein degradability. Three diets at 14% crude protein included 10.8% soybean meal (diet 1), 8.0% corn gluten meal plus .5% urea (diet 2), or 10.6% corn gluten meal (diet 3) as the protein source. Diet 4 was 17% crude protein with soybean meal and diet 5, 12.6% protein with urea. Protein disappearance after 24-h nylon bag incubation in rumen fistulated steers was 54, 49, 43, and 58% for diets 1 to 4. Diets were fed to 45 Holstein cows averaging 35 (±14) days postpartum with a 2-wk covariate and a 6-wk experimental period. Cows were fed diet 1 during the covariate period. Treatment means adjusted by covariance for the variable and days postpartum, for average daily milk yield, milk fat percent, milk protein percent, milk lactose percent, and solids-corrected milk were 30.8, 2.95, 3.07, 5.08, and 28.5; 32.9, 2.40, 2.96, 5.20, and 26.2; 34.2, 2.71, 2.88, 5.18, and 27.8; 36.7, 2.81, 3.09, 5.10, and 28.5; 31.7, 2.43, 2.93, 5.24, and 25.4 for diets 1 to 5. Decreasing dietary protein degradability at a 14% crude protein increased milk production, decreased milk protein percent and had a quadratic effect on milk fat percent. Increasing dietary protein percent raised milk yields, milk protein percent, and solids-corrected milk yield.

Performance of First Lactation Dairy Cows Fed Complete Rations of Several Ratios of Forage to Concentrate

Seventy-four Holstein cows in first lactation averaging 27.6 mo of age at parturition were fed blended diets ad libitum with ratios of forage to concentrate (dry basis) of 80:20, 65:35, 50:50, or 35:65 from 7 through 16 wk of lactation. Two-thirds of the forage in each diet was early bloom alfalfa-brome hay and one-third was well matured corn silage. Daily yields of actual milk, 4% fat-corrected milk, and solids-corrected milk were each adjusted for preexperimental yield by covariance.Actual milk yield increased curvilinearly and solids-corrected milk yield increased linearly, whereas fat-corrected milk yield was unaffected as ratios of forage to concentrate decreased. Milk fat percent decreased and milk protein percent increased curvilinearly whereas lactose increased linearly with decreasing ratios of forage to concentrate. Feed intake increased as did live weight and heart girth but not wither height as ratios of forage: concentrate decreased.

Performance, Rumen and Blood Metabolites in High-Yielding Cows Fed Varying Protein Percents and Protected Soybean

Three groups of 20 multiparous high-yielding cows were fed during the first 122 days after calving diets containing 16, 16, and 20% crude protein. Protein of soybean meal in the diet of only the first group was protected with formaldehyde. The calculated crude protein intakes, including maintenance, per kilogram of milk, were 71, 76, and 96g. Average 122-day milk yields of cows were 40.4, 38.9, and 38.4 kg/day, but solids-corrected milk yields were almost identical. Rumen liquor ammonia and urea concentration in blood plasma were 8.6, 10.0, and 17.3 mg/100ml liquor and 8.4, 8.8, and 15.4 mg/100ml plasma. Cows fed the protected soybean diet had lower total volatile fatty acid concentrations in rumens and higher molar percentages of propionate but lower percentage of butyrate than cows of the two other groups. Likewise, during wk 7 to 17 after calving, cows of the protected soybean group had a lower fat and protein milk content. Conception rates were 69, 56, and 44%, and open days were 84, 98, and 102.

Influence of Dietary Protein Concentration on Milk Production by Dairy Cattle in Early Lactation

In a 3×2 factorial experiment, 21 mature cows (third or later lactation) and 21 heifers in first lactation were fed complete rations containing 12.4, 15.1, or 17.7% crude protein in the dry matter. Rations contained in dry matter, 10% hay, 30% corn silage, and a 60% mixture of high moisture corn, soybean meal, and a mineral-vitamin premix.Average daily milk production of heifers was not affected by protein in ration in Periods 1 or 2 (5 to 6 or 12 to 13 wk postpartum). For cows, milk production responded quadratically in Period 1 and linearly in Period 2. In Period 2, response was linear for solids-corrected milk yield by cows but not by heifers. Cows fed the 15.1% ration had greater prepartum subcutaneous fat measurements and lower dry matter intake (15.7 kg/day) during Period 1 than cows fed 12.4 or 17.7% crude protein (18.0 and 19.9 kg/day). Increases in protein resulted in higher urea nitrogen and total protein concentrations in plasma, but rumen pH and total volatile fatty acids were not affected.Apparent nitrogen digestibility increased linearly with protein. Although nitrogen balance was not affected by protein concentration, conversion of nitrogen intake to milk nitrogen decreased linearly as protein intake increased.

Effects of Dry or Ensiled Feeds and Protein Percent on Milk Production and Nitrogen Utilization by Lactating Cow

In two 2×2 factorial experiments, 28 cows in first and later lactation (Trial 1) and 28 cows in second and later lactation (Trial 2) were fed rations containing either dry (low nitrogen solubility) or ensiled (high nitrogen solubility) feeds with low (14%) or high (16%) concentrations of crude protein. Rations were formulated with hay or hay crop silage and dry shelled corn or high moisture shelled corn in a 50:50 ratio (Trial 1) or 40:60 ratio (Trial 2) of forage to concentrate in the dry matter. Soybean meal was used to alter the protein content.Protein percent had no effect on milk yield or milk composition in either trial, although nitrogen digestibility was greater on high protein diets. Solids-corrected milk yield and milk fat percent were lower when nitrogen solubility of the ration was increased in Trial 2 but not in Trial 1. Analysis of nitrogen balance data indicated higher conversion of nitrogen of feed to nitrogen of milk for low solubility diets in Trial 1 and high solubility diets in Trial 2.

All Silage Forage Programs for Dairy Cattle. II. Performance Through Three Lactations

Corn silage, blended corn silage and haycrop silage (60:40 dry matter), or blended corn silage and chopped hay (60:40 dry matter) each were fed ad libitum as the sole forage to 15 Holstein-Friesian females from birth to completion of three lactations. Between 18 mo of age and first parturition animals on corn silage treatment were fed .5kg protein supplement per day. After first parturition, concentrate was fed to a maximum of 12kg (first lactation) or 14kg (second and third lactations) per day during 4 wk postpartum. Thereafter, concentrate was fed according to production. Protein was balanced by adding 1kg supplement per day to corn silage treatment during lactation.Measurements of body weight and wither height as well as body condition at first calf were similar across treatments.Cows fed the silage-hay combination consumed more forage and total dry matter than those fed corn silage alone in each period except second lactation. Differences were greatest in first lactation. Milk and solids-corrected milk yields were higher for animals fed corn silage and hay than for corn silage alone in first lactation. Milk composition and solids-corrected milk yield per unit dry matter intake were unaffected by treatment.

Brewer's Yeast Slurry. II. A Source of Supplementary Protein for Lactating Dairy Cattle

Brewer's yeast slurry and soybean meal each were incorporated in complete rations at 6 and 12% of dry matter to increase crude protein from 13% (negative control) to 15 and 17%. Thirty Holstein cows were blocked on age, stage of lactation (average 200 days), and milk yield (average 19.4kg) and assigned to treatments within blocks. Data analysis was on differences between the 28-day treatment and average of preceding and subsequent control periods when the 15% protein soy diet was fed.Milk yield, milk component yields, and differences of protein percent were higher on the supplemented rations than on the negative control. Differences in protein and solids-corrected milk yield increased with dietary crude protein. Source of supplementary protein did not affect production response. A taste panel test detected no difference in organoleptic quality of milk representative of each treatment ration.Molar percent of rumen acetic acid was higher on the yeast supplemented rations while propionic and isovaleric acids were lower. Blood urea nitrogen was also lower from supplementation with yeast slurry. Apparent digestion coefficients for dry matter, gross energy, crude protein, and acid detergent fiber were all higher on the yeast supplemented rations than on soy diets.The effect of yeast slurry stored for 0, 7, or 14 days on rumen measures was compared with a soybean meal control diet in a 4×4 Latin square experiment with rumen fistulated cattle. Storage time had no consistent effect on measures of rumen or blood.

The effect of supplementation of the diet of lactating Jersey cows with varying levels of acetic acid

SummaryTwO Latin-square experiments using lactating Jersey cows have been made to determine the response to 4 levels of acetic acid given as a supplement to diets fed at Woodman's Standards. The response in milk yield and composition to daily supplementary infusions of acetic acid is curvilinear, the point of inflexion occurring between the levels of 450 and 600 ml acetic acid/d. The direction of responses to the 150-ml level of infusion varied between the experiments. At the 600-ml level of addition the non-significant increases in milk fat, protein and lactose yield led to a significant increase in solids corrected milk yield. The effects of acetic acid infusion on the composition of the milk fat were determined.

Feeding Value of Protected Animal Tallow for High Yielding Dairy Cows

Supplement containing animal tallow protected with formaldehyde-treated soybean meal was introduced into concentrates at 0, 21, and 32% and fed ad libitum to Holstein cows in a changeover design during early lactation. Primary objective was to determine whether feeding protected tallow in concentrates would increase voluntary energy intake, milk yield, and fat test without adversely affecting other milk components or flavor. Intakes of total dry matter and from concentrates were decreased, dry matter from forage increased, and energy intake was unchanged by feeding protected tallow at each percent. Treatments did not affect milk yield significantly but did increase output of 4% fat-corrected milk. Solids-corrected milk yield and gross energetic efficiency were not improved consistently by feeding protected tallow. Supplement increased fat tests by .43 and .76 percentage units over control when fed at 21 and 32% but lowered protein and lactose content of milk. Cholesterol, formaldehyde, and flavor of milk were unaffected by treatment whereas cholesterol and triglycerides in blood plasma rose dramatically during short-term feeding of protected tallow. Blood glucose remained unchanged.

Response of Cows during Early Lactation to a Low Energy Ration for 4 Days1

A low-energy ration was fed to 38 Holstein and Jersey cows which were between 18 and 101 months of age (4 to 64 days postpartum). The ration, primarily alfalfa hay and cottonseed meal, provided only 30% of the energy but 90% of the protein requirements for lactation. Milk production declined, but milk fat yield was relatively constant due to a dramatic increase in milk fat percentage. Solids-corrected milk yield declined from 22.5 to 19.1 kg during the 4 days of low energy intake. Blood glucose declined and blood ketones increased by day 4. Serine, alanine and glycine were reduced in plasma while valine, isoleucine, leucine and cystine were elevated by the low dietary energy. Initial (day 0) milk yield was related positively to final (day 4) production of milk, milk fat, solids-not fat and solids-corrected milk. The percentage of solids-not fat in milk was lower with increased parity. Blood glucose was lower for cows having the shortest postpartum interval. Alanine, serine and phenylalanine were higher as the postpartum interval increased. Valine, leucine, isoleucine, proline and aspartic acid in plasma declined with increasing age of cows. Glutamic acid was lower in plasma of cows with heavier initial body weight, and methionine was lower in plasma of higher producing cows. For energy restriction studies, cows should be similar in age and production level and be used at the same point of lactation.