Daily dry matter intake to sustain body weight of mature, nonlactating, nonpregnant cows

To quantify the relationship between DM consumption, the ability to sustain BW per unit of DMI (BW stasis), and days to reach BW equilibrium among diverse cattle breeds, weekly individual cow BW and DMI data were recorded for mature, nonpregnant, and nonlactating cows sampled from Angus, Braunvieh, Charolais, Hereford, Gelbvieh, Limousin, Pinzgauer, Red Poll, and Simmental breeds. Within each breed, cows were assigned to receive 1 of 4 daily DM allowances (56, 76, 93, or 111 g·BW⁻⁰.⁷⁵, kg) of a ground alfalfa hay-corn grain-based diet. Cows were housed in pens (space for 4 animals/pen) in open-front barns and fed individually using head gates. During the first 60 d of the experiment, BW were recorded every 28 d, after which BW were recorded on a weekly basis until the cows were determined to have attained BW equilibrium. Individual cows were determined to be at BW equilibrium when the rate of weekly BW change did not differ from 0 over an 8-wk period. The number of days to reach BW equilibrium was not affected (P > 0.79) by breed but was affected by the daily DM allowance (P < 0.003). The number of days required to attain BW equilibrium was greater as the rate of feeding (g of DM fed·BW⁻⁰.⁷⁵) increased and ranged from 103 to 136 d. Within breed linear and the pooled quadratic regressions were significant for BW. Observed breed differences varied with feeding rate. Weight stasis estimates for mature Red Poll cows (68.3 ± 3.8) differed (P < 0.05) from estimates for all the breeds, with the exception of Limousin (72.0 ± 3.8), Braunvieh (74.0 ± 4.8), and Pinzgauer (75.5 ± 3.8) cows at the lowest feeding rate. At the 111 g·BW⁻⁰.⁷⁵ daily DM allowance, the estimates for Limousin (82.2 ± 3.8) were greater (P < 0.05) than for the other breeds, with the exception of the Pinzgauer (81.0 ± 4.3) and Braunvieh (75.7 ± 3.9), which were similar to the remaining breeds in the study (P > 0.05). The change in rank of breed estimates for BW stasis suggests a breed x nutrition interaction for BW stasis.