Getting into goat growth
23 May 2019
Supplementation is the strategy of providing animals with small quantities of a specific nutrient or nutrients to meet requirements for a target level of productivity. There is limited information regarding the response of rangeland goats to specific protein and energy supplements. An understanding of the likely response of rangeland goats to supplementation is essential to support producers making supplementation decisions.
To determine the likely responses of rangelands goats to supplementation MLA has commissioned research at The University of Queensland to develop;
- response relationships to a range of supplements which may be used by rangeland goat producers, and
- a simple Excel‐based supplement calculator which incorporates these relationships. The project will involve a review of the nutritional requirements of rangelands goats and four separate feeding and live weight gain experiments.
The first of the four experiments was recently completed.
Fifty‐four young entire male rangelands goats (17kg live weight) were sourced from the Dirranbandi district, Queensland, and relocated to the University of Queensland's Gatton campus in September. The goats were fed a low quality mitchell grass hay ad lib with increasing amounts of cotton seed meal, whole cotton seed and lucerne chaff, representing different types of protein sources, for 77 days (Phase 1). Feed intake, weight gain, diet quality, metabolites in the plasma and rumen ammonia‐N concentration were measured.
The goats were held in individual inside pens to allow for the collection of individual feed intake data with the experiment conducted during a period of increasing day length to avoid any potential impacts of winter stasis on results. At the conclusion of Phase 1 goats were then fed either lucerne hay or a commercial pellet ad lib, with free access to mitchell grass hay (Phase 2) in group feeding pens.
The following results are preliminary and analysis of all data is yet to be completed.
During the Phase 1 of the experiment, bucks fed the mitchell grass hay essentially maintained weight while bucks supplemented with the highest level of cotton seed meal gained an average 60g/day. Bucks supplemented with lucerne chaff gained 40g/day. Bucks fed whole cotton seed had low and variable intake of whole cotton seed and this was reflected in low and variable growth rates. The maximum growth rate recorded for an individual buck was 91g/day across the 77-day experiment. Total dry matter intake ranged from 2.0 to 3.5% of live weight, which was within the expected range for ruminants fed these diets. During Phase 2, bucks fed lucerne hay gained 146g/day (range ‐ 80-210g/day) compared to 200g/day (range ‐ 109-300g/day) for bucks fed the commercial pellet.
The live weight of bucks entering Phase 2 (15 to 25kg) had no influence on their subsequent growth rates when fed lucerne hay or commercial pellets.
These preliminary results demonstrate that potential exists to significantly increase growth rates of young entire male rangelands goats and significant variation in growth exists even within a small mob of goats that were of a similar live weight. The project will now attempt to develop cost‐effective supplementation strategies to achieve the higher growth rates observed during Phase 2.