Technical annual report 2000-01
Dept. of Regional Development, Primary Industry, Fisheries and Resources technical annual report; Department of Regional Development, Primary Industry, Fisheries and Resources technical and annual report; Reports; PublicationNT; Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295
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Agriculture -- Northern Territory -- Periodicals; Fisheries -- Northern Territory -- Periodicals
Dept. of Primary Industry and Fisheries
Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295
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Technical Annual Report 2000/01 57 Table 1. Productivity results from VRRS breeder herds 1997 May 2001 Cow genotype Calf genotype Weaning weight (kg) Weaning rate (%) Breeder efficiency (kg weaner/100kg breeder) Brahman 1 Brahman 183 75.8 31.3 Droughtmaster Droughtmaster 181 83.9 35.7 Brahman 2 Charolais, Brahman 186 80.2 34.3 F1 (Brahman, Charolais) Charolais, Brahman 185 82.1 31.6 Similar groups of young mixed steers are run with each adult breeder herd for 12 months and their relative performance (weight gain) over 12 months used as an indicator of grazing conditions available within that paddock. Table 2 shows the average steer performance over the period 1997 2001 from each herd. Table 2. Weight gain of young steers run in adult breeder paddocks 1997 2001 Brahman 1 Droughtmaster Brahman 2 F1 (Brahman, Charolais) Average annual weight gain (1997/98 2000/2001) (kg) 133 134 123 128 Genotype in column headings refers to adult breeder herd and NOT the steers. Translating relative steer weight gains into probable impacts on breeder productivity is not well understood. Table 1 shows that the Droughtmaster herd has consistently outperformed the other herds in terms of weaning rate (83.9%) and breeding efficiency (35.7 kg weaned per 100 kg breeder mated), and the Brahman 1 herd has returned the lowest values for these two performance indicators (75.8% and 31.3 kg, respectively). Table 2, however reveals that grazing conditions in the Droughtmaster paddock have been similar to the Brahman 1 paddock, thus it is reasonable to assume that in pure herds, Droughtmasters show superior productivity to Brahmans under similar conditions. For crossbred herds, the Brahman 2 herd produced a lower weaning rate than the F1 herd (80.2% versus 82.1%) but a higher breeding herd efficiency (34.3 kg versus 31.6 kg per 100 kg breeder mated). Data presented in the 1999/2000 Technical Annual Report show a mature weight and consequent stocking rate difference of 15% between Brahmans and F1s with the F1s having a higher mature weight and therefore lower stocking rate to achieve similar total mature weight per paddock. Table 1 reveals that even though the stocking rate of the F1s is 15% lower, weaning rate in only 2% higher and weaning weight is virtually identical. For this reason, the Brahman 2 herd has the highest breeding efficiency of the herds producing crossbred progeny. This has been achieved despite the grazing conditions, as indicated by steer performance, being lowest in the Brahman 2 paddock. Summarising, pure Droughtmasters have performed best of all herds, closely followed by the Brahman herd producing crossbred progeny. Pure Brahmans have lowest performance indicators and the F1 herd does not produce sufficient extra weaners of heavier weight to compensate for the lower number of breeders in this herd. Full analysis and reporting of results is a major task for 2001/2002.