Productivity through weaning of nine breeds of cattle under varying feed availabilities: I. Initial evaluation.

The effect of varying dry matter availability on the conversion of dry matter resources to weight of calf at weaning was evaluated for nine breeds of cattle; Angus, Braunvieh, Charolais, Gelbvieh, Hereford, Limousin, Red Poll, Pinzgauer, and Simmental were recorded for 5 yr. Within each breed, four cows were assigned to each of four feeding levels of dry matter intake: 58, 76, 93, or 111 g of DM/wt75. Cows remained on their assigned diet regimen throughout the study. Individual cow consumption, daily feed allowance adjusted for refusal, was recorded weekly. Production information included birth and weaning weight of the progeny, calving rate, and cow weights and condition scores. Cows were exposed to bulls of the same breed for 90 d. Reasons for cow replacement included failure to conceive in two successive years, injury, Caesarean section, chronic illness, and death. Response to dry matter intake (DMI) was curvilinear and differed among breeds (P < .10) for calving rate, calf survival, and weight of calf weaned per cow exposed. Significant differences occurred among the breeds for the linear response to DMI for cow weight and condition score. The response to DMI was curvilinear for birth weight (P < .10), but the response did not differ among breeds (P > .20). Red Poll exhibited more effective conversion at DMI less than 4,000 kg/yr, but breeds with greater genetic potential for growth and(or) milk production (Gelbvieh, Charolais, Braunvieh, Simmental, Pinzgauer, and Limousin) were more efficient at DMI greater than 6,000 kg/yr. Ranking for biological production efficiency (weight of calf weaned-cow exposed-1.kg DMI of cow-1) through weaning among breeds of cattle varied with dry matter intake.