The biological performance of pigs at high temperature.

Abstract

Animal production in Australia THE BIOLOGICAL PERFORMANCE OF PIGS AT HIGH TEMPERATURE C. VAJRABUKKA*, C.J. THWAITES* and D.J. FARRELL** Livestock in Australia are frequently subjected to temperature stress. Limited data are available on the influence of high temperature on the biological performance of pigs. The results of a preliminary study on the effects of manipulating dietary energy and protein concentrations on the performance of pigs kept at high temperatures are reported here. Six groups of five Landrace x Large White entire males, initially weighing 45 kg, were grown to 90 kg. Four groups were kept in a hot room diurnally variable: 12 h at 35OC and 12 h at 25OC, and two groups were held at 22OC as controls. Individual feeding stalls allowed recording of feed intake for each pig. The four diets offered ad 2%. to the pigs in the hot room were (a) high energy-high protein (HH), (b) high energy-low protein (HL), (c) low energy-high protein (LH) and (d) low energy-low protein (LL). Diets (b) and (d) were also offered to two groups of pigs held at 22OC. To determine digestible energy (DE) of the diets, faecal output was estimated using Cr203 as an inert marker in the feed. The chemical composition of samples of feed and faeces was determined using standard procedures. Results are shown in Table 1. TABLE 1 Dietary analysis and effects of temperature treatment on groups of five pigs on different dietary regimes Although there was no effect (P>O.O5) of diet on weight gain of pigs in the hot room, pigs in groups 2 and 4 on diets HL and LL grew more slowly (P<O.O5) with a poorer (PxO.05) FCR, and a lower (PcO.05) dressing percentage, than pigs at 22OC on the same diets. Conversion of dietary energy (DE) to gain was better (PcO.05) at 22OC th an at 35/25 for pigs on diets HL and LL, and on the high-, compared to the low-energy diets irrespective of temperature. There are at least three reasons for the few significant nutritional effects: (a) wide variation in response of individual pigs to high temperature, (b) slight leg injuries sustained by three pigs in prototype feeding stalls reduced groups 2, 4 and 5 to four pigs per group, and (c) variation among similar diets in DE concentration. The work is proceeding with particular attention to these problem areas. * Department of Animal Science and ** Biochemistry and Nutrition, University of New England, Armidale, N.S.W. 2351. 510