Response of calves to diets that varied in amounts of ruminally degradable carbohydrate and protein.

Holstein calves were used wk 1 to 12 after birth to evaluate three sources of nonstructural carbohydrates that differed in ruminal degradability (corn, barley, and dried whey) with two sources of CP (normal and extruded soybean meal) that also differed in ruminal degradability. Nonstructural carbohydrates were most degradable in the dried whey diets and least degradable in the corn diets, and protein was more degradable in soybean meal than in extruded soybean meal. Pelleted diets were formulated to be isonitrogenous at 18% CP and contained (DM basis) 20% ground alfalfa hay, the respective carbohydrate and protein sources, vitamins, minerals, and antibiotic premix. All calves received 4.5 kg/d of milk during wk 1 to 4 and 2.3 kg/d during wk 5. The BW gains during wk 1 to 12 were higher (.80, .70, and .70 kg/d) for calves fed corn than for those fed barley and dried whey, respectively, and were slightly higher for calves fed extruded versus normal soybean meal (.76 and .71 kg/d). Corresponding DMI (1.47, 1.34, and 1.31 kg/d) were higher for calves fed corn than for those fed barley and dried whey and were higher for calves fed extruded versus normal soybean meal (1.43 and 1.32 kg/d). Trends in BW gains and feed intakes for wk 1 to 5 and 6 to 12 were similar. Feed to gain ratio was similar for all diets in all periods. The BW gains of calves tended to be greater when they were fed diets containing nonstructural carbohydrates and protein that was less ruminally degradable.

Heterodyne efficiency of quadrant photodetectors.

In this paper we compare quadrant heterodyne efficiencies. Differences in efficiencies between circular and square detectors are small while relative spacing between quadrants is more important in its effect on efficiencies. Spot size relative to detector size is also important. The effect of angular misalignment on efficiency is smallest for the Airy-Airy combination.

Response of cows consuming adequate selenium to vitamin E and selenium supplementation prepartum.

A 2-yr study of 195 parturitions was to evaluate the prepartum need for supplemental vitamin E and selenium by cows consuming diets that contained ample amounts of selenium (.1 to 2.0 ppm selenium). One-half of the cows were injected with 68 IU vitamin E and 5 mg selenium per 45.4 kg body weight approximately 21 days prepartum. Incidences of retained placenta and calving difficulty were similar for treated and control cows. There was a lower incidence of retained placenta (7.5%) for cows that calved during fall, whereas incidence was greater than 20% in cows that calved during the rest of the year. Serum vitamin E and selenium concentrations in treated cows doubled within a day after injection, then declined to concentrations typical of untreated cows within 8 and 3 days postinjection, respectively. Serum carotene, vitamin A, and vitamin E concentrations were similar for treated and control cows and were elevated in cows that calved during the summer and fall, possibly because cows dry during the grazing season were pastured. However, discriminant analysis of 21-day prepartum serum data indicated that serum concentrations of carotene, vitamins A or E, or selenium would not predict accurately the retention of the placenta. Colostrum and 4-day milk from treated and control cows contained similar amounts of vitamin E and selenium.

Initiation of parturition in dairy cows with dexamethasone. II. Response to dexamethasone in combination with estradiol benzoate.

Parturition was initiated in 26 Holstein cows given dexamethasone (4.4 mg/100 kg body weight) in combination with 25 mg estradiol benzoate intramuscularly at day 273 of gestation. Parturition occurred at 40.8 +/- 9.6 h after injection. Twenty-six control cows had an average gestation length of 281.5 days. Calving difficulty was not different although birth weight of calves was 2.5 kg less for induced cows compared with control cows. Severity of udder edema did not differ between groups. Average daily milk production for the first 9 wk of lactation was lower (24.2 versus 27.7 kg) from induced than control groups. Incidence of retained placental membranes was 50 and 4% for induced and control cows. Serum estrogens were lower (290 versus 601 pg/ml) in induced than in control cows 2 days prior to parturition. Groups did not differ inserum calcium, phosphorus, magnesium, days to first heat, days to first breeding, days to conception, or in fat, protein, and total solids content of colostrum. Casein in colostrum of induced cows was lower. Results of California Mastitis Tests at 15 and 30 days postpartum were similar.