Crossbreeding experiment with beef and dual-purpose sire breeds on Danish dairy cows

The experimental design and objectives are outlined for a crossbreeding experiment with European beef breeds as sire breeds and RDM (Danish Red), SDM (Black Pied Danish) and Danish Jersey as dam breeds.Results from a calving survey of 1006 single calvings are presented. Gestation length, birth weight and calving performance were strongly influenced by breed of sire, breed of dam and sex of calf. The variation in gestation length seemed to have only a slight effect on birth weight. The variation in birth weight had a strong effect on calving performance.The ranking of the sire breeds in descending order according to the frequency of unasisted calvings (which varied from 70 to 26 percent) was as follows: Hereford, Limousin, Danish Red and White Cattle, Simmental, Blonde d'Aquitaine, Chianina, Charolais and Romagnola.     

Crossbreeding experiment with beef and dual-purpose sire breeds on Danish dairy cows III. Daily gain,feed conversion and carcass quality of intensively fed young bulls

Beef production characteristics of 254 intensively fed young bulls are described. The results are part of a beef × dairy crossbreeding experiment, where sires of eight European beef and dual-purpose breeds were used on cows of RDM (Danish Red Cattle) and SDM (Black Pied Danish Cattle).Daily gain and feed conversion were influenced by the sire breeds. Charolais, Blonde d'Aquitaine and Simmental crosses showed the highest daily gain, followed by Romagnola, Danish Red and White, Chianina, Limousin and Hereford crosses.Carcass composition and carcass conformation were strongly influenced by sire breed with Blonde d'Aquitaine and Limousin crosses producing the most valuable carcasses followed by Chianina, Charolais, Romagnola, Simmental, Danish Red and White and Hereford crosses in descending order.The analysis showed a sire breed × weight/age interaction in carcass composition traits, due to sire breed differences in maturity. That demonstrates the importance of serial slaughtering in breed comparison experiments. Hereford and Limousin produced the earliest maturing crosses and Danish Red and White and Blonde d'Aquitaine the latest maturing crosses.     

Implanting young bulls with zeranol from birth to four slaughter ages: I. Live measurements, behavior, masculinity and carcass characteristics

Seventy-two Simmental bull calves were allotted randomly at birth to either a zeranol (Ralgro) implanted (I) treatment or a nonimplanted control (C) group. At birth, bulls assigned to the I treatment were implanted with 36 mg of zeranol and reimplanted at average intervals of 84 d until slaughter. Calves were weaned at 7.2 mo, preconditioned for 2 wk, and randomly assigned by treatment to slaughter ages of 12.0, 13.8, 15.7 and 17.4 mo and fed an 83% concentrate diet until slaughter. At 7.7 mo and all slaughter ages, live weights and hip heights were similar (P greater than .10), but I bulls had lower (P less than .05) masculinity scores than C bulls. Scrotal circumferences for I bulls were smaller (P less than .05) at 7.7, 12.0, 13.8 and 15.7 mo, but similar (P greater than .10) at 17.4 mo to C bulls. Behavioral observations of passive bunting, mounting attempts, facility rubbing and overall activity were less (P less than .05) for I bulls than C bulls from 12.0 to 13.8 mo but similar (P greater than .10) from 13.8 to 17.4 mo. Aggressive bunting was less (P less than .05) for I bulls during five of the seven observation times for the 12.0-to-13.8-mo period only. Slaughter and carcass weights and dressing percentages were similar (P greater than .10) for I and C bulls. Skeletal maturity and marbling scores, fat thicknesses, yield grades and 9-10-11th rib fat percentages were higher (P less than .05) and lean maturities, forehead hide weights, high dermis thicknesses, femur measurements and 9-10-11th rib bone weights and percentages were lower (P less than .05) for I than C bulls. Rib eye areas and carcass masculinity traits of jump muscle and crest of I bulls were less (P less than .05) at 13.8 mo but reached similar (P greater than .10) development to C bulls at 15.7 mo. Testicle weights of I bulls were lighter (P less than .05) at 12.0, 13.8 and 15.7 mo, but similar (P greater than .10) to C bulls at 17.4 mo. Growth traits (all weights plus hide and femur measurements) and maturation traits (skeletal and lean maturities, marbling scores, fat thicknesses and pizzle eye sizes) increased the most from 12.0 to 13.8 mo and 13.8 to 15.7 mo, respectively. We concluded that implanting young bulls with zeranol from birth to slaughter had minimal effects on live measurements, improved carcass desirability and delayed masculinity and behavioral development.