Twenty-four Jersey calves were randomly assigned to 1 of 4 treatment groups (6 calves per group). Pooled colostrum from first milkings (colostrum high in IgG1, 84 mg/mL) of multiparous cows was fed to treatment groups 1 and 2. Pooled colostrums from second and third milkings (colostrum low in IgG1, 31.2 mg/mL) of multiparous Jersey cows were fed to calves in treatment groups 3 and 4. The quality and timing of colostrum feeding was as follows: group 1 were fed (high IgG1 colostrum) 4 L at 0 h (birth); group 2 calves were fed (high IgG1 colostrum) 2 L at 0 h (birth) and 2 L at 12 h; group 3 calves were fed (low IgG1 colostrum) 4 L at 0 h (birth); and group 4 calves were fed (low IgG1 colostrum) 2 L at 0 h (birth) and 2 L at 12 h. Mean serum Ig() was 38.66, 45.66, 13.81 and 9.95 mg/mL in groups 1 to 4, respectively. At 48 h of age, calves fed colostrum with higher concentrations of total ingested IgG1 (groups 1 and 2) had significantly higher serum protein and IgG1 concentrations than calves fed low IgG1 colostrum at 48 h of age (groups 3 and 4). Mean apparent efficiency of IgG1 absorption was measured at 48 h; calves (group 2) receiving 2 L at birth and 2 L at 12 h of high IgG1 colostrum had higher mean apparent efficiency of IgG1 absorption than calves (group 4) fed 2 L of colostrum that was low in IgG1 at birth and 12 h (31.2 and 18.2% in groups 2 and 4, respectively). Results suggest that Jersey calves should receive 2 separate feedings of high quality colostrum to maximize the colostral IgG1 absorption.

Four multiparous Holstein cows averaging 49 DIM and fitted with ruminal cannulas were utilized in a 4 x 4 Latin square design with 21-d periods to determine the effects of diets containing high oil corn grain and tallow. Cows were fed diets of alfalfa haylage and concentrate (37:63, DM basis) for ad libitum intake. Treatments were 1) control, no added fat; 2) high oil corn grain replacing regular corn grain; 3) high oil corn grain and 2.5% tallow; and 4) high oil corn grain and 5% tallow. Intake of DM, milk production, and yields of milk fat, milk protein, milk SNF, and 4% FCM were not affected by dietary fat, although DMI tended to be lower when cows were fed 5% tallow. Percentages of protein and SNF in milk were lower when cows were fed diets containing fat. Percentage of milk fat was lower when cows were fed diets containing tallow. Supplemental fat decreased total VFA concentrations in ruminal fluid. Cows fed high oil corn had a greater molar proportion of acetate and a larger acetate to propionate ratio in ruminal fluid than cows fed high oil corn and tallow. Digestibility of total fatty acids decreased when tallow was added to diets containing high oil corn. No differences were observed among treatments for total tract apparent digestibilities of DM and fiber or utilization of energy and N. Dietary high oil corn and 5% tallow tended to decrease DMI and to alter ruminal fermentation characteristics.

Eighteen Holstein heifers were fed long and chopped coarse and fine alfalfa hay ad libitum to evaluate effects of physical form on digestion and chemical composition of feed and fecal particles and to examine the applicability of a sinusoidal model to chewing behavior. Recordings of jaw movement were divided into 1-h segments for analysis. Least square mean size of fecal particles from coarse and finely chopped diets were 290 and 297 micrometers as compared to 227 micrometers on long hay. Intakes of dry matter were greater an digestibilities lower for chopped as compared to long hay. Crude protein content of separated feed and fecal particles increased as particle size decreased. Neural and acid detergent fiber concentrations decreased in feed and feces with decreasing particle size. Lignin content of feed particles decreased as particle size decreased, whereas for fecal particles lignin as a percent of cell wall followed a "U" shaped pattern of declining then increasing as size decreased. Patterns were sinusoidal for eating and ruminating long and chopped hays and total chewing (eating and ruminating) of long hay. Our results suggest a gradual effect on chemical degradation and physical detrition of digesta particles and chewing behavior as forage particle size decreased.

In two experiments with multiparous Holstein cows, the effects of feeding supplemental nicotinic acid or nicotinamide on milk production and metabolite changes associated with early lactation were measured. In Experiment 1, 30 cows were assigned to three groups. The treatment groups received 6 g nicotinic acid or 6 g nicotinamide per head per day beginning 2 wk prepartum to 12 wk postpartum. Control group received no treatment. Cows receiving nicotinamide produced more milk (wk 9, 11, and 12) and had higher milk fat test (wk 1 and 4) than did controls. Concentrations of beta-hydroxybutyrate in blood serum (wk 4) were lower for cows receiving nicotinic acid or nicotinamide. Serum glucose concentration (wk 4 to 6) was higher and FFA (wk 4) were lower for cows receiving nicotinamide than for controls. In Experiment 2 with six multiparous Holstein cows, the effects of feeding nicotinamide on metabolic changes associated before, during, and after a 48-h period without feed initiated at 4 wk postpartum were studied. The treatment groups received 12 g nicotinamide per head per day beginning 2 wk prepartum to 4 wk postpartum. The control group received no treatment. Supplementing nicotinamide to lactating cows had no effect on serum glucose, beta-hydroxybutyrate, or free fatty acids before, during, or after 48-h period without feed.

Efficacy of detecting subclinical mastitis by electrical conductivity of milk was compared with that of other indirect methods including chloride, sodium, potassium, lactose, bovine serum albumin, and somatic cell count of milk. Quarter samples of foremilk, strippings, and bucket milk were obtained from 75 cows at the afternoon milking over 8 wk. Infection of quarters was ascertained by bacteriological analysis. Electrical conductivity, chloride, and sodium content of milk were more accurate for predicting infection status of quarters than were other variables. Most variables were more accurate in predicting infection when measures were in strippings rather than in foremilk or bucket milk. For measures in strippings, misclassifications by electrical conductivity were 11.2 and 15.5% for false positives and false negatives. The accuracy of the electrical conductivity of milk for detection of subclinical mastitis compared favorably with all indirect methods. Accuracy of detection and adaptability to both manual and automatic cow-side mastitis detection systems indicate that the method has considerable potential as a screening test for subclinical mastitis.

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Forty-two calves (mean 10 d of age) that spontaneously contracted diarrhea were used to test the therapeutic value of an oral rehydration solution with or without whole milk. Therapy began on the first feeding after a fecal score was > 2 (five-point scale). Amounts (percentages of BW daily) of milk and oral rehydration solution on d 1 and 2, 3 and 4, 5 and 6, and 7 for treatments 1, 2, and 3 were 1) 0 and 10, 5 and 5, 7.5 and 2.5, 10 and 0% (in two feedings); 2) 2.5 and 10, 5 and 7.5, 7.5 and 5, 10 and 0% (in two feedings); 3) 10 and 10, 10 and 5, 10 and 2.5, 10 and 0% (in three feedings). Oral rehydration solution was fed 15 min after milk. Fecal score, rectal temperature, packed cell volume of whole blood, concentrations of glucose and electrolytes in serum, and strong ion difference of serum were unaffected by treatments. Calves given treatment 3 gained BW throughout the experiment, whereas those given treatments 1 and 2 lost BW during the first 3 d of therapy. Fecal cultures indicated that 70% of calves were infected with Cryptosporidium on d 1 of therapy. No mortality occurred. Whole milk and oral rehydration solution fed to calves did not adversely affect calves or prolong or worsen diarrhea but promoted gain of BW.

Microbial degradation of plant fiber is an important factor limiting the utilization of forages by ruminant animals. The objectives of this study were to determine the composition and rate and extent of digestion of cell walls of normal and brown midrib (bmr) genotypes of two sorghum ✕ sudangrass [Sorghum bicolor( L.) Moench] hybrids and to assess the relationship between cell wall composition and digestibility. Plants, harvested at three stages of maturity, were separated into leaf blade, leaf sheaths, and stems and analyzed for fiber constituents, structural carbohydrates, and, alkali‐labile phenolic composition. Fiber digestion kinetics were determined utilizing in vitro batch cultures. Brown midrib genotype were lower (P < 0.05) in neutral detergent fiber(NDF) and acid detergent lignin concentrations than normal genotypes. Leaf components had a greater (P< 0.05) NDF concentration than stems; however, leaf cell walls were much less lignified than stem cell walls. There were no differences between genotypes (P > 0.05) in neutral sugar composition or in the xylose to arabinose(X:A) ratio. Morphological components varied in the concentration of all neutral sugars, except mannose, and in the X:A ratio. Brown midrib genotypes had a significantly lower trans‐p‐coumaric acid concentration and a p‐coumaric acid to ferulic acid ratio than normal genotypes. There was no difference (P>0.05) between genotypes in the rate of NDF digestion, which averaged 0.0413 and 0.0.95 h‐1 for bmr and normal genotypes, respectively; however, bmr genotypes. had a greater (P<.05)72 h extent of NDF digestion when compared to normal genotypes. The results of this study indicate that the p‐couramic acid concentration and the linear xylan content are important factors limiting the rate and extent of cell wall digestion.