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This study was conducted to evaluate the predictions of dry matter intake (DMI), average daily gain (ADG), and faecal nitrogen (N) excretion by the Cornell Net Carbohydrate and Protein System Version 6.1.26 (CNCPSv6) in China. A total of 71 bulls from two imported breeds, Limousin and Simmental, and three local breeds: Luxi, Jinnan and Qinchuan were selected in China. Data required by the CNCPSv6 model were collected, and model predictions were generated for animals of each breed. The regression equation between observed and predicted DMI for these cattle was: YOBS = 0.93XCNCPS + 0.48 (R2 = 0.94; P < 0.001), with an intercept not different from zero and a slope not different from unity. The proportion of deviation points lying within the range –0.4 to 0.4 kg · d–1 was 90.1%. The regression equation between observed and predicted ADG was: YOBS = 1.07XCNCPS – 0.05 (R2 = 0.92; P < 0.001), with an intercept not different from zero and a slope not different from unity. About 78.9% of points fell within the range –0.1 to 0.1 kg/d for these cattle. Model-predicted faecal N excretion for the cattle breeds was close to the observed values. The regression equation between observed and predicted faecal N excretion was: YOBS = 1.04XCNCPS – 1.48 (R2 = 0.94; P < 0.001), with an intercept not different from zero and a slope not different from unity. About 73.3% of the points fell within −4 and 4 g per day. These results show that the CNCPSv6 model using actual feed fractions can give good predictions of DMI, ADG and faecal N excretion with different beef cattle breeds in China.
Inferences on competitive interactions between white-tailed deer Odocoileus uirgi- nianus (Zimmermann, 1780) and cattle were made using information on diet composi­tion and quality. We hypothesized that dietary overlap between deer and cattle would increase with cattle density and that quality of deer diets would be higher in areas not exposed to cattle than in areas that were stocked with moderate to high cattle densities. Three treatments were delineated in McCurtain County, Oklahoma (heavy cattle stocking), and Howard (moderate to light cattle stocking) and Pike (no cattle stocking) counties, Arkansas. Treatments were similar with respect to soils and vegetation but differed with respect to cattle stocking rate (ie number of cattle/ha). Deer and cattle diets and concentrations of fecal nitrogen (FN) {an index to dietary quality) were determined from feces that were obtained from .12 randomly selected collection areas (4/treatment) from October 1986 to October 1988. Dietary overlap of deer and cattle was highest in winter and lowest in summer. Dietary overlap of deer populations was lowest for populations exposed to heavy cattle stocking and no cattle stocking, which suggested that competition between the deer and cattle occurred in winter. Fecal nitrogen was iowest in deer feces collected from treatments with cattle stocking in February but higher in August and October. Both dietary quality and dietary overlap suggested possible competitive interactions between deer and cattle in winter. However, higher dietary forb and dietary quality for deer in summer exposed to cattle suggested that cattle can facilitate growth of early successional plant species in pine habitats.
We tested the reliability of fecal nitrogen (FN) to predict dietary nitrogen (DN) in two sika deerCervus nippon Heude, 1884 populations with greatly differing habitats. One was near the village of Nishiokoppe (area A) and the other was on Nakanoshima Island (area B) in Hokkaido, Japan. To estimate FN, we washed feces through a sieve, and diet was identified based on rumen-content analysis. The diet in area A was mostly composed of grass and legumes of agricultural origin, with browse being only a minor component. In contrast, browse such as deciduous foliage was the main component of the diet in area B. Dietary nitrogen was significantly regressed by FN within specific areas. On the other hand, the DN-FN-relationship had a similar slope but significantly different intercepts between areas. DN-FN-relationships differed between diets with and without an agricultural component, irrespective of browse. Thus, the difference in the DN-FN-relationship between areas was explained by differences in dietary composition. We therefore conclude that FN may be useful in predicting DN in diverse dietary situations regardless of the ratio of browse in the diet of free-ranging ungulates, but that dependence on agricultural pastures may hinder the utility of FN as an index of DN.
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