A comparison of the wether progeny of Border Leicester, Cheviot, and Merino rams mated to Merino ewes.

Abstract

A COMPARISON OF THE WETHER PROGENY OF' BORDER LEICESTER, CHEVIOT AND MERINO RAMS MATED TO MERINO EWES S. T. DAWE Border Leicester, Cheviot, and Merino rams mated to Merino ewes were compared in terms of the meat production of their progeny. Each ram breed was joined with approximately 100 Merino ewes in April in the three years 1964-66. Birth weight (P < 0.05) and incidence of lamb deaths (P c<O.Ol) were lower for Merino progeny than for either of the other breeds. Cheviot progeny were superior to Merinos but inferior to those of Border Leicester sires in growth rate, bodyweight at slaughter, carcass weight and financial return per lamb (all P < It is concluded that, as prime lamb sires, the Border Leicester rams were superior to the Cheviot rams which were superior to the Merinos. 0.05). Summary I. INTRODUCTION There is little critical information on the use of the Cheviot breed of sheep in Australia. Cheviot and Dorset Horn rams have been compared as prime lamb sires (Hamilton, Pattie and Godlee 1966) but the Cheviot x Merino ewe has yet to be evaluated as a prime lamb mother. Information is also required on the performance of Merino ewes as prime lamb mothers. As a prelude to such an evaluation, lines of Border Leicester x Merino, Cheviot x Merino, and Merino ewes were bred from a common flock of Merino ewes. This breeding programme provided an opportunity for a comparison of Border Leicester, Cheviot and Merino rams as prime lamb sires. II. MATERIALS AND METHODS (a> General The Cheviot rams came from different commercial studs each year whereas all the Border Leicester and Merino rams were obtained from Cowra and Trangie Agricultural Research Stations, respectively. In mid April in 1964, 1965 and 1966, the rams were joined with a flock of Merino ewes at Yanco Agricultural Research Station. The same ewes were randomised each year before joining into three equal sized groups of approximately 100 ewes. Each group was joined with two rams of one breed. Except for the six week joining and lambing periods the ewes were run as a single flock. *N.S.W. Department of Agriculture, Agricultural Research Station, Leeton, N.S.W. The wether lambs were all slaughtered when the average bodyweight of the slowest growing breed group had reached approximately 30 kg. Valuations 4 were made by commercial livestock agents, and carcasses were graded by a Meat Inspector. Skins were valued by commercial buyers on a breed group basis in 1964 and 1965, and individually in 1966. (b) Statistical Analyses The growth rate of each lamb was calculated from the measurement of bodyweight nearest to 12 weeks of age, and the actual age in days at that time. The total value for each carcass was arrived at by multiplying the price/kg by the cold carcass weight and adding the respective skin value. Data for the -ewe lambs were included only in the analyses of the incidence of twin births and of lamb losses. Where one lamb of twins had died within a week of birth, the surviving partner has been classified as a single lamb in all analyses except that of birth weight. Analyses of percent twin births, percent lambs lost, percent first grade carcasses, and dressing percentage were made by th.e angular transformation method of Claringbold, Biggers and Emmens ( 1953). The remaining parameters were analysed by methods appropriate for disproportional subclass numbers (Snedecor 1956). Cold carcass weights were adjusted for age each year by covariance, and a test of significance was made on these adjusted means. III. RESULTS Differences between sire groups in the number of ewes which lambed and in the incidence of twin births were not significant (Table 1). Deaths of the pure bred Merino lambs from birth to marking were fewer (P < 0.01) than of the crossbreds. Birth weight, growth rate, slaughter data and monetary returns are presented in Table 2. Merino lambs were bettered (P < 0.05) by Border Leicester progeny in birth weight, growth rate per day, body-weight at slaughter, and cold carcass weight, and by Cheviot progeny in all of these factors except growth, rate to TABLE 1 Fertility Data (Means for 3 years 1964-66). 205 TABLE 2 Bodyweight and Slaughter Data SFigures are for singles and twins combined. . six weeks and dry Bkin weight. There were significantly (P < 0.01) fewer Merino lambs graded as first quality carcasses. Lambs sired by Border Leicesters were superior (P < 0.05) to lambs sired by Cheviots in growth rate per day, bodyweight at slaughter, cold carcass weight .and dry skin weight. Differences between the three breeds in dressing percentage were not significant. Price per kg of carcass was lower (P < 0.05) for Merinos than for either of the other breeds and the price per kilogram of skin ( 1966 only) was greater 206 (P < 0.01). Differences between .the three breeds in total return per lamb were significant (P < O.d5), but so too was the breed x year interaction (P < 0.05). Although the preslaughter valuations were not statistically analysed, it was evident that the Border Leicester cross lambs were considered superior by the valuers. IV. DISCUSSION The superiority of the Border Leicester in this study was due mainly to greater lamb growth rate which resulted in heavier carcass and skin weights. Although there were no overall differences in quality between carcasses of Cheviot and Border Leicester sired lambs, as measured by grading and price per kilogram, the critical factor `was carcass weight. The same situation applied with return per skin, where quality was similar but skins of Border Leicester origin were heavier. In 1965 there were slightly higher dressing percentages and prices per kg of carcass in favour of the Cheviot cross lambs. These advantages, together with a smaller difference in bodyweight in comparison with the other years, produced similar monetary returns per lamb for both Cheviot and Border Leicester progeny in this year, resulting in the significant breed x year interaction. Merino lambs were consistently inferior to Border Leicester lambs in al1 factors except price per kilogram of skin in 1966. Growth rate of the Merino progeny was not at first different from that of th.e Cheviot progeny but lagged as the .lambs grew older so that at slaughter there were large differences in bodyweight. I The slaughter of all lambs at the one time resulted in a wide range of bodyweights between and within breeds. Some of the Border Leicester and Cheviot lambs were too heavy, and some of the Merinos too light, for slaughter under commercial conditions. Consequently, many of the Merinos were at a disadvantage. This situation, however, arose from the poor growth of the Merino progeny and was therefore a treatment effect. On the other h.and, some of the heavier carcasses of the other breeds were penalised in terms of price/kg because they were too fat. It is concluded that the Border Leicester rams used in this study were superior to the Cheviots as meat producing sires and these in turn were superior to the Merinos. V. ACKNOWLEDGMENTS The author wishes to thank Mr. I. D. Killeen for his guidance. Thanks are due to the Managers and staffs of Yanco Agricultural Research Station and A. J. Bush and Sons (Yanco) Pty. Ltd., and to Messrs. E. Hackney, I. McClure, A. Moon, J. Breed, K. Montgomery and M. Strahan, who valued and appraised the experimental animals. VI. REFERENCES C LARINGBOLD , P. J., B IGGERS, J. E., and E MMENS , C. W. (1953). Biometrics 9: 467. HAMILTON. B. A., PATTIE, W. A., and GODLEE, A. C. (1966). Proc. Aust. SOC. Anim. Prod. 6: 206. S NEDECOR , G. W. ( 1956). 'Statistical Methods'. (State University' Press : Iowa). 207