Research Abstracts for November 1998

Nutrition Update
Volume 9 No.3, November 1998

Nelson, M.L. 1997. Escape protein supplementation of steers fed grass silage-based diets. J. Anim. Sci. 75:2796.

Beef steers (ave.wt. = 300 kg) were fed rations formulated for 0.8 kg gain/day and consisting of 67.5% wheat or oat silage, 20.5% barley, and 12% supplement. Dietary treatments were graded levels of supplemental escape protein (EP) from corn gluten meal (0 to 213 g/d EP) or animal by-products (1:1:1 DM mixture of blood, feather and meat and bone meals, 0 to 317 g/d of EP). Wheat silage and oat silage contain substantial soluble protein (39 to 78% of crude protein) and have rapid rates of insoluble nitrogen disappearance, therefore, metabolizable protein may be the first-limiting nutrient for steers consuming silage diets. Live weight gain was increased by 0. 15 kg/day and maximized when steers were supplemented with 135 g/day of EP. Supplementation with 223 or 317 g/day of animal by-product EP increased live weight by 0.27 kg/day.

Supplemental escape protein was needed to increase live weight gain of steers consuming ensiled forage diets due to low escape protein contents of silages and barley and limited microbial protein synthesis.

Kincaid et. al. 1997. Zinc oxide and amino acids as sources of dietary zinc for calves: effects on uptake and immunity. J. Dairy Sci. 80:1381.

Calf starter diets were formulated to contain 60 ppm of Zn(control), 150 or 300 ppm of Zn in the form of ZnMet and ZnLys, or 300 ppm of Zn in the form of ZnO to compare relative bioavailability and effects on immunity. Holstein heifer calves were weaned at wk 5 and fed the starter diets from wk 6 to 12. Feed intakes and body weight gains were similar among treatments. Concentrations of Zn in serum were only elevated in calves fed 300 ppm of Zn as ZnMet and ZnLys. Concentrations of Zn in liver were significantly elevated by 300 ppm of Zn in the form of ZnMet and ZnLys but not by the other Zn treatments or by the control. There was no significant treatment effect on the immune paramaters measured.

Addition of 300 ppm of Zn from ZnMet and ZnLys increased liver and serum concentrations of zinc compared to the other treatments. Although liver concentrations were increased with Zn-Met and Zn-Lys, there was no advantage in terms of calf performance or immune function.

Muehlenbein et. al. 1998. Pre-calving copper supplementation on maternal transfer of copper to the calf and passive transfer of immunity. J. Animal Sci.76:360.

Seventy-seven first calf heifers were randomly allotted to three treatments: (1) a copper depletion supplement (600mg Fe, 5mg Mo), (2) an inorganic supplement (600mg Fe, 5mg Mo and 200 mg CuS0₄ and (3) an organic supplement (600mg Fe, 5mg Mo, 100mg Availa-Cu, Zinpro). Cows were individually fed the supplements for at least 45 days prior to calving. Liver biopsies were taken to determine the trace mineral status of cows prior to the initiation of the trial and on both cows and calves at 10 days after calving. A colostrum

sample was collected prior to the calf nursing and analyzed for IgG and trace mineral content. Cow liver Cu levels were 58 ppm before supplementation. At day 10 after calving, cow liver Cu levels in treatment 1 had decreased to 23 ppm, treatment 2 levels increased to 88 ppm and treatment 3 levels were not significantly different from base levels. No significant differences were found among treatments in calf liver or in calf serum copper concentrations. Copper supplementation tended to increase the IgG levels of calf serum.

Copper supplementation, from either inorganic or organic copper sources, did not result in changes in calf copper status, making the transfer of copper from cow to calf constant and independent of intake.

Swenson et. al. 1998. Trace mineral supplementation effects on first-calf beef heifer reproduction, milk production and calf performance. J. Animal Sci.76:

Experimental supplements were formulated to provide 25 ppm Cu, 72 ppm Zn, 41 ppm Mn, 1 ppm Co, and 5 ppm Mo on a daily DM intake basis. Treatments also included time of supplementation initiation, 60 days versus 30 days precalving. Angus heifers(118) were allotted to the following treatments which were individually fed on alternate days: 1) complexed(organic) at 60 days(CX60), 2) complexed at 30 days (CX30) 3) inorganic at 60 days (IN60) and 4) inorganic at 30 days (IN30) and Mo only (CON). Sodium molybdate was fed in free-choice salt to provide 8 ppm Mo on a daily basis for 30 days presupplementation. Milk production was significantly higher for CX60 (8.9 kg/d) compared to CON (6.8 kg/d) and other treatments were intermediate. However, adjusted 205 day weaning weights were similar among groups. Heifers consuming complexed mineral had exhibited estrus earlier in the breeding season, 98 days compared to inorganic mineral at 106 days and CON 108 days post-partum.

Providing organic minerals to heifers for 60 days precalving reduced the calving to first estrus interval but had no effect on incidence of calf scours or adjusted 205 day weaning weights.

 

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