Browsing by Subject "Lambs -- Nutrition"
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Item Performance of lambs grazing pearl millet at four levels of herbage allowance(Texas Tech University, 1987-12) Martinez, ArturoKnowledge of the quantitative relationship between herbage allowance and production per animal and per unit area of land provides the basis for a successful grazing strategy. A successful grazing strategy implies that an optimum balance between production per animal and per unit area of land has been achieved. The objective of this research was to determine the quantitative relationship between herbage allowance and gain/lamb and gain/ha when grazing Tifleaf I dwarf pearl millet (Pennisetum americanum (L.) Leeke). Levels of herbage allowance were 4, 6 , 9 and 12 kg/100 kg of lamb weight/day. Experimental design was a randomized complete block with three field replications. Experimental grazing lasted 70 days in each of two consecutive summers (1984 and 1985) and rotational grazing with 7-day use and 28-35-day rest was followed, Gain/lamb and per ha was different (P<.05) among allowances. Average gains/lamb over the two years were 65, 68, 90 and 100 g/day for the 4, 6, 9 and 12% allowances, respectively. Gains/ha were 663, 478, 434 and 374 kg for the 4, 6, 9 and 12% allowances, respectively. Gain/lamb was positive and linearly (P<.01) related to level of herbage allowance. The gain/ha-herbage allowance relationship was described by a quadratic equation (P<.05). Gain/ha decreased linearly from the 4 to Q% allowances and leveled off after the S% allowance. After the 3rd-4th day of grazing, intake by lambs was restricted at the 4 and 6% allowances apparently by high fiber content. Final model (R^ = 68) from stepwise regression to estimate daily gain of lambs included the variables (X) sward height reduction by grazing, hemicelluloses after grazing, NDF before grazing, herbage mass before grazing and ADF after grazing. Pearl millet is a good summer pasture for limbs. Based on these findings, grazing dwarf pearl millet at a 6-7% herbage allowance could be expected to provide a reasonable compromise between gain/lamb and gain/ha.Item The effects of source of zinc on performance, nutrient utilization, and immune function in ruminants(Texas Tech University, 2002-05) Nunnery, Greg AlanThree experiments were conducted to evaluate the availability of different sources of Zn for ruminants. In the first experiment, lambs were supplemented with no supplemental Zn (control) or 20 mg of Zn/kg from Zn sulfate, Zn methionine, or Zn propionate to determine the effect of source of Zn on Zn absorption and retention in each of two collection periods. The control diet was removed from the analysis of the first collection period because it was contaminated with Zn. In both collection periods, absorption (P < 0.05) and retention (P < 0.05) of Zn was greater by lambs receiving Zn propionate than by lambs in the other treatments. In the second experiment, the effect of supplemental Zn on heifer performance during receiving and finishing phases was evaluated. Treatments were no supplemental Zn (control) or 75 mg of Zn/kg from Zn sulfate, Zn methionine, or Zn propionate. During the receiving phase, control heifers had a higher (P < 0.05) d-35 body weight (BW) and were more efficient (P < 0.05) than heifers in the other three treatments. Heifer morbidity did not differ (P > 0.10) among treatments for the 35-d receiving phase. Dry matter intake and daily gain did not differ (P > 0.05) among treatments for the 168-d finishing period; however, feed efficiency was poorer (P > 0.05) for control heifers than for the average of heifers in the other treatments. Carcass characteristics generally did not differ (P > 0.05) among treatments. The third experiment evaluated the effects of no supplemental Zn (control) or 75 mg of Zn/kg from Zn sulfate, Zn methionine, or Zn propionate on the humoral immune response of heifers injected with ovalbumin (OVA). Specific OVA antibody titers did not differ (P > 0.10) among the four treatments on any of the days measured. Results suggest that Zn propionate seems to be a more available source of Zn based on the data from the lamb trial; however, no major differences between the sources were observed for morbidity, performance, or the humoral immune response of heifers.