Abstract:
COMMERCIAL EVALUATION OF A TROPICAL BREED DEVELOPED EXPERIMENTALLY * ** + T.H. RUDDER, K.G. BEAN,+ J.W. LAPWORTH and G.W. SEIFERT Summary The experimentally developed Belmont Red was compared with cormmercially bred bulls of other breeds. On the basis of wt per d of age at 179, 361 and 501 d steers sired by Santa Gertrudis, Droughtmaster and Belmont Red bulls were generally similar. Steers sired by Brahman bulls were marginally heavier, while steers sired by Hereford bulls were lightest at 179 d and intermediate at 361 d and 501 d. . Females sired by Hereford and Belmont Red bulls had higher reproductive performance than females sired by Brahman, Santa Gertrudis and Droughtmaster bulls. This would negate any difference in steer performance, and in terms of beef production the more fertile breeds would enjoy an advantage. I. INTRODUCTION The Belmont Red breed of cattle is a by-product of the main research programme of the Tropical Cattle Research Centre, Rockhampton. This breed was developed by initially mating Africander bulls with Hereford and Shorthorn cows, and then inter se mating the resultant F and subsequent 1 generations. Initially, this genotype was produced for comparative studies with similarly developed Brahman x British, and Hereford x Shorthorn genotypes. These studies were designed to define the traits that affect productivity in a tropical environment. The Africander x British, and the Brahman x British cattle have shown superior growth rate (Kennedy and Chirchir 1971), resistance to Boophilus microplus (Seifert 1971), and survival rates (Frisch 1973) to the Hereford x Shorthorn cattle. Markedly superior reproduction rates have been exhibited by the Africander x British cattle in the F and subsequent generations when compared with similar Brahman x Bri i? ish, and Hereford x Shorthorn cattle (Seebeck 1973). When compared with the Brahman x British cattle, growth rates were marginally lower, and this is partially due to the lower tolerance to gastro intestinal helminths by the Africander x British cattle (Seifert 1971, Turner and Short 1972). These data suggest that the Belmont Red cattle will be important to commercial producers, especially in the semi-arid areas of the sub tropics and tropics. This paper reports initial results of a trial designed to compare the Belmont Red with commercially bred cattle under commercial management practices, II. These data * Beef Cattle + Division of ** Beef Cattle MATERIALS AND METHODS on 'Mt. Eugene', Qld, 4700. Qld, 4700. 4715. were collected from the commercial herd Husbandry Branch, Q.D.P.I., Rockhampton, Animal Genetics, C.S.I.R.O., Rockhampton, Husbandry Branch, Q.D.P.I., Biloela, Qld, 89 Jambin, where average annual rainfall is 674 t 135 mm, with a predominantly summer incidence. The breeding herd was supported on land capability classification (Rosser et al. 1974) class IV - VI land which . grows pastures of primarily Heterpogon spp.; Bothriochloa spp., and Dicanthium spp. Herd replacement heifers were transferred to class III land growing predominantly Panicum maximum var. trichoglume pasture at approximately six months of age (weaning) and were returned to the breeding herd at approximately 15 months of age. Steers were transferred to the class III at approximately six months of age (weaning) and remained there for the duration of the trial. Cows with approximately half Brahman and half Hereford components were mated with Brahman, Santa Gertrudis, Droughtmaster and Belmont Red bulls. Hereford bulls .were mated to cows of primarily 5/8 to 3/4 Brahman / component. Data collected from the steer portion of these matings were analysed by the least squares method (Harvey 1960) for wt per d of age at 179 d, I 361 d and at 501 d. These data were from the steers born during 1972 and 1973. Following the joining period Oct. 1974 to Feb. 1975, data from the heifer portion of the calves born during 1972 and 1973 were analysed for percentage pregnancy attained and estimated month of conception. Per cent pregnancy was derived by coding 1 for pregnant, and 0 for nonpregnant. Estimated month of conception was measured from estimated foetal age determined by rectal palpation and coding from 5 to 1 for Oct. to Feb. conceptions respectively. The least square models used to analyse both sets of data are manifest in the tables for analyses of variance. III. RESULTS AND DISCUSSION Table 1 gives the analyses of variance for wt per d of age'at the three ages observed, Estimated least square means and constants for breed of sire effects are shown in Table 2. Breed of sire effects were significant at each of the ages represented, but the magnitude of the constants decreased as age increased. At 501 d of age differences between the steers sired by Santa Gertrudis, Droughtmaster and Belmont Red bulls were negligible. The significant year by breed of sire interaction suggests that differences in environmental conditions will alter the ranking of tropically adapted genotypes, Differences in the ranking of breed of sire groups at different ages may be a reflection on how differing genotypes react to differing environmental conditions within a yr rather than an age difference between these genotypes, Analyses of variance for percentage pregnancy attained, and estimated month of conception are shown in Table 3. Table 4 shows the least square means and constants for breed of sire effects. The breed of sire effects on percentage pregnancy show an advantage to the females sired by Hereford and Belmont Red bulls. These data agree well with the trend one would predict from the Belmont results (Seebeck 1973)* Higher reproductive performance is probably largely due to the effect of higher hybrid vigour derived by crossing relatively diverse genotypes. Breed of sire did not have a significant effect on estimated month of conception. However, it is interesting to note that females sired by Hereford, and Belmont Red bulls tended to conceive earlier in the joining season. The regression on cqw wt was highly significant for estimated month of conception (b = .0;15 - .002). This shows that heavier females 90 TABLE 1 Analyses of variance for wt per d of age at 179 d, 361 d and at 501 d TABLE 2 Estimated least square means and constants for wt per d of age at 179 d, at 361 d, and at,501 d TABLE 3 Analyses of variance for percentage pregnant, and estimated month of conception 91 TABLE 4 Estimated least square means and constants for percentage pregnant, and estimated month of contention conceived earlier in the joining season. Fvr percentage pregnant, the was a factor influencing percentage pregnant. These regressions remove the effect of any differences in wt between groups and allow a better estimate of reproductive differences. Although these data represent initial results they suggest that the Belmont Red will have a useful role in commercial herds containing half Brahman component, Equally important is the supportive evidence that the results obtained by the research group at the Tropical Cattle Research Centre can be transposed to the commercial situation. IV, ACKNOWLEDGmNTS Thanks are due to Mr. P.J. Maynard for making cattle available, and to Miss B. Lill and Miss L. Sedgman for collation of data and typing. v. REFERENCES FRISCH, J.E. (1973). Australian Journal of experimental Agriculture and Animal Husbandry, 13: 127, HAR.VEY, W.R. (196O)e Dzted States Department of Agriculture, Agricultural Research Science, NO. A.ReSe-20-8e KENNEDY, J.F., and CHIRCHIR, G.I.K. (1971). Australian Journal of experimental Agriculture and Animal Husbandry, 11: 593. ROSSER, J., SWARTZ, GeLI, DAWSON, N.M., and BRIGGS, ??%a (1974)e Division of Land Utilization Technical Bulletin NOe 14, Queensland Departmen .t of Primary Industries, Brisbane, May 1974. Journal of agricultural Science, 81: 253. SEEBECK, ReMe SEIFERT, GeW. (1971). Australian Journal of agriculturayResearch, 23: 17 7e TURNER, H;Ge 3 and SHORT, A.J. (1972). Australian Journal of agriculEra1 23: Research, C 177, (1973) l 92