LACTATION CHARACTERISTICS OF 9 BREEDS OF CATTLE FED VARIOUS QUANTITIES OF DIETARY ENERGY

Milk yield data were collected by weigh-suckle-weigh procedures at approximately 14, 28, 56, 84, 112, 138, 156, 184, and 212 d postpartum for mature Angus, Braunvieh, Charolais, Gelbvieh, Hereford, Limousin, Red Poll, Pinzgauer, and Simmental cows over a 4-yr period. Individual cows were fed at one of four energy intake levels. Parameters characterizing lactation curves for 431 lactations from 179 cows were estimated by nonlinear regression. Differences due to breed, level of energy intake, and the two-factor interaction between breed and level of ME allowance for scale and shape parameters of lactation curves and derived estimates for time of peak lactation, yield at time of peak lactation, and for total yield for a 210-d lactation period were evaluated. Breed and energy intake level were significant sources of variation for all traits. Pooled over energy levels, daily yields at time of peak lactation of Braunvieh, Gelbvieh, and Pinzgauer were greater (P < .05) than those of Angus, Charolais, Hereford, and Limousin. Simmental and Red Poll were intermediate. Total lactation yield of the Braunvieh exceeded (P < .05) that of all other breeds with the exception of Gelbvieh. Hereford produced less milk than (P < .05) the other breeds. The response in yields at time of peak lactation as energy allowances increased for Braunvieh, Charolais, Gelbvieh, Limousin, and Pinzgauer cows was linear and resulted in higher yields at this time. Linear increases in total 210-d yield and times of peak lactation were observed for all breeds with the exception of Hereford.