Beef production from Charolais, Charolais X Shorthorn and Simmental sired calves from Jersey and Jersey X Hereford cows under grazing conditions.

Abstract

BEEF PRODUCTION FROM CHAROLAIS, CHAROLAIS X SHORTHORN AND SIMMENTAL SIRED CALVES FROM JERSEY AND JERSEY X HEREFORD COWS UNDER GRAZING CONDITIONS M.P. DELAND* and P. SAUNDERS** Summary The value of Charolais, Charolais x Shorthorn and Simmental bulls in beef production from Jersey and Jersey x Hereford cows was assessed under grazing conditions in the South East of South Australia. Steers from the 1973 calf drop were killed at an average age of 619 days and those from-the 1974 drop at 281 days. There were no significant . differences in growth rate between sire breed groups in either year. Carcasses of 300 kg with 8 mm of fat were obtained from 6190day old steers, Depending on breed of sire, calf weights at weaning (average age 281 days) were 73% to 90% of concurrent. dam weight. I. INTRODUCTION breds are commonly thought to be po or numbers on Struan Research Centre, 'nd required little assistance whils t 9 unpublished data). The Jersey .irements than the straightbreds ) Y and young Jersey crossbred cows cow kept than 'did any other cross1975). Although Jersey and Jersey cross meat producers, females used in small South Australia, had high fertility a calving to the Charolais (M.P. Deland crossbreds had'lower maintenance requ tested by Thomas and Cartwright (1971 had heavier weaned weight of calf per breds tested at Clay Centre (U.S.D.A. Jersey realise low matings of However, as diture, use and Jersey crossbred females surplus to dairy requirements offspring from market values due to low carcass wei&.ts; Jersey sires over beef heifers also realise low prices. cost of cows in a breeding herd is a major capital`expenof these crosses could greatly reduce this overhead. and progeny available, sired by Use of sires of large European breeds such as the Charolais Simmental should improve growth rate and carcass conformation of of Jerseys. As there are only limited numbers of purebred bulls however, we compared the progeny from crossbred bulls with those purebreds. .This trial was designed to find out if the progeny of Jersey and Jersey crossbred cows grazed at pasture under South Australian conditions would produce carcasses suitable for the vealer and pre-packaged cut trades. II. MATERIALS AND METHODS -The private property on which the cattle grazed is situated 39 km SW. of Naracoorte, South Australia, being improved perennial pastures being of subterranean clovers, strawberry clover, phalaris and ryegrass. * Struan Research Centre, Box 618, Naracoorte, South Australia, 5271. ** Present address: P.M.B. 38, Kingston, South Austxxlia, 5275. 81 Jersey and Jersey x Herefordheifers were purchased in 1971 and 1972 at local and Victorian sales, In 1972 heifers and cows were mated. All animals had calved at least once before mating in 1373. Mating began in June each year. Semen from 12 Charolais and 12 Simmental bulls was used. Semen from a# Charolais x Shorthorn bull which ranked top out of 10 contemporaries on growth rate was used in 1972 and two Charolais x Shorthorn bulls of unknown rank were mated naturally in 1973. Cows in oestrus were marked by epididectomised bulls fitted with chinball marking devices. The cows marked each day were yarded the next morning and inseminated. Semen was allocated to ensure proportional distribution, between breed of cow, of the semen of each bull. The Charolais x Shorthorn bulls were paddock mated with cows which had been selected at random prior to mating. The same mating- period was used for natural and artificial insemination. After mating, cows grazed as one mob. At birth, calves were ear tagged and weighed. Difficult calvings were noted and assisted by the manager as he saw fit. All calves grazed at pasture throughout their lifetimes. Most male calves were castrated within 60-90 days of birth in 1973 and in 1974 all male calves were castrated at birth. Steer data only are used for 2000day weight and carcass analysis. Calf weights (at c.200 days) were adjusted for date of birth to 200 days, Calves from the 1973 drop were weaned at an average age of 270 days and slaughtered at an average age of 619 days whereas all calves of the 1974 drop were weaned and slaughtered at an average age of 281 days. Livestock buyers determined when steers were ready for slaughter; those slaughtered at 281 days for the vealer trade, and those slaughtered at 619 days for the pre-packaged cut trade. Carcass composition was assessed from shin dissection (Butterfield and Thomas 1973) and a note taken of carcasses considered yellow by the meatworks staff. At weaning of the 1974 drop, cows and calves were weighed. Weights were analysed by analysis of variance in a 2 x 3 factorial design and the subsequent calculation of least significant differences, III. -RESULTS With the addition of one dead, assisted calf (Simmental x (Jersey x Hereford)), calving data are given in Ta,ble I. TABLE I 82 Jersey x Hereford dams gave birth to significantly heavier calves to the Simmental than did Jersey dams. There were no significant differences in 2000day weights of calves (table 2). TABLE 2 Carcass weights of 1974 drop Simmental-sired calves were heavier than of calves sired by Charolais x Shorthorn bulls out of Jersey x Hereford cows. However, there were no significant differences in carcass composition between breed groups in this drop (table 3). TABLE 3 No significant differences in carcass weight were-noted in the 1973 drop. However, Charolais-sired carcasses were generally leaner than other groups as measured by muscle and fat percentage, No carcasses in the 1974 drop were considered yellow; four out of the forty 1973 drop were considered too pigmented for the Japanese market. Calf weight, as a percentage of cow weight at weaning, is given in table 4.- These values, and the growth rates achieved, are higher than 83 those for any other breed groups for which data (M.P. Deland unpublished) are available at Struan Research Centre, TABLE 4 IV. DISCUSSION The carcasses produced from systems using Jersey and Jersey x Hereford dams mated to Charolais, Cha,rolais x Shorthorn and <Simmental bulls have been described. The vealer trade requires carcasses which are covered by fat but which weigh less than 180 kg. Most carcasses produced by the 281 day group were considered ideal for this trade. There is an increase in the demand for pre-packaged cuts relative to demands -for carcass beef. Carcasses of 300 kg and 8-12 mm of fat are sought for this trade because killing chains are fully utilized without penalty rates for over-weight carcasses. The 6190day old carcasses met . this requirement and top prices were received for all except one carcass0 .The adjusted 2000day live weights achieved are heavier than those for the Jersey crosses at Clay Centre (U.S.D.A. 1975) and for certain crosses observed in South Australia (Deland, Jakes and Giles 1974). Although only three Charolais x Shorthorn sires were used, the results indicate that high growth rates are possible usi.ng such crossbred bulls v. ACKNOWLEDGEMENTS . Finance for this project was provided by the Australian Extension Services Grant and the Australian Meat Research Committee. We are grateful to Mr. V. O'Grady of Bokara Props. for the use of facilities and staff of their property and to personnel of Struan Research Centre who have assisted during the experiment. VI. REFERENCES BUTTERFIELD, R.M. and THOMAS, P& (1973) - Manual of Techniques for Field Investigations with Beef Cattle. C.S.I.R.O., Canberra, 1973. DEL&ND, M.P., JAKES, J.E., and GILES, W. (1974) - Proceedings of the Australian Society of Animal Production. 10 : 17. THOMAS, R.C., and CARTWRIGHT, T.C. (1971) - BeefTattle Research in Texas, 1971, Texas A & M University PoR. 2980. U.S.D.A. (1975) - Germ Plasm Evaluation Program Progress Report No. 2 ARS-NC-22 April 1975. 84