a comparison of lactating dairy cows performance fed rations formulated by national research council 2001 and cornell pennsylvania miner
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چکیده
the precision and accuracy of national research council (nrc 2001) vs. cornell pennsylvania miner (cpm) softwares were evaluated. sixteen lactating dairy cows (8 in second lactation and 8 in third, with days in milk of 55 ± 31, body live weight = 641 ± 53 kg, milk yield =31.2 ± 2.5 kg/day), were assigned to individual pens in a randomized complete block design, with two blocks of two ration treatments (each treatment including 4 cows in second lactation and 4 in the third). the cows were fed rations formulated by nrc 2001 (a) and cpm (b), as totaly mixed rations (tmr) for 90 days. the adaptation consisted of a period of two weeks from the beginning of the experiment. the average milk yields of cows fed with diet a vs. b were 31.11 and 31.9, respectively with no significant difference observed between the two groups for the mentioned trait (p>0.05). there was no significant difference observed for dry matter intake (dmi) in the two ration treatments (p>0.05), the average dry matter intake of diets a vs. b being 22.9 and 22.33 kg/day, respectively. both nrc 2001 and cpm underpredicted dmi (-0.63 and -2.43 kg/day respectively) while the national research council model predicting dmi somehow more accurately (in lactating dairy cows) than cpm. average daily crude protein intakes for diets a vs. b were 3618 and 3438 g/d, respectively (p
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علوم دامی ایرانجلد ۴۰، شماره ۳، صفحات ۰-۰
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