Introduction systems of swine production in the tropics, could be

Livestock Production Science 66 2000 223–234 www.elsevier.com locate livprodsci Adverse effects of tropical climate on voluntary feed intake and performance of growing pigs a , b b Dominique Rinaldo , J. Le Dividich , J. Noblet a ´ Institut National de la Recherche Agronomique , Unite de Recherches Zootechniques, 97170 Petit-Bourg, Guadeloupe, F.W.I b Institut National de la Recherche Agronomique , Station de Recherches Porcines, 35590, Saint Gilles, France Received 24 July 1998; received in revised form 16 December 1999; accepted 31 January 2000 Abstract Four replicates were conducted to determine the effects of tropical climate and season on voluntary feed intake and performance of pigs and their carcass characteristics at 90 kg, as compared to a control environment CE. CE was characterized by ambient temperature of 208C and relative humidity RH of 75. Under tropical climate, ambient temperature averaged 24.68C and RH 84 during the cool season CTC and 27.38C and 82 during the warm season WTC respectively. Ninety-six Large White pigs were used between 15 and 35 kg live weight P1 and, as 36 of them were slaughtered at 35 kg, the remaining pigs were used from 35 to 90 kg P2. In the CTC, neither voluntary feed intake, nor average daily gain, feed:gain ratio or carcass characteristics significantly differed from CE in P1 and P2 pigs. In the WTC, the 13 decline in feed intake of P2 pigs P , 0.001 induced a 13 diminution in growth rate P , 0.05. In the WTC, fat percentage of the carcass was reduced by 3.2 units P , 0.001, whereas less fat was deposited in backfat P , 0.001 and more fat retained in leaf fat P , 0.001, as compared to the CTC. Also in the WTC, the reduction in the weight of internal organs led to a 1.8 unit improvement in killing-out percentage P , 0.001. Data indicated that in the tropics, growth performance varied with the season and that during the warm season feed intake was a major limiting factor to growth rate.  2000 Elsevier Science B.V. All rights reserved. Keywords : Pig-feeding and nutrition; Environment; Tropics; Feed intake; Performance; Carcass characteristics

1. Introduction systems of swine production in the tropics, could be

due to various factors including the tropical climate. Growth performance of pigs reared in tropical Both high air temperature and humidity are charac- areas is often regarded as low even when balanced teristics of tropical climate in the Carribean area. diets and improved breeds are used Egbunike, Numerous studies have shown that ambient tempera- 1986. This low level of performance, which is a ture has direct effects on voluntary feed intake and major limiting factor to the development of intensive therefore performance of pigs Verstegen et al., 1978; Nichols et al., 1982; Close, 1989. Most of these studies deal with the assessment of additional Corresponding author. Tel: 1590-25-59-33; fax: 1590-25-59- feed requirement in the cold. Conversely, less in- 36. E-mail address : rinaldoantilles.inra.fr D. Rinaldo formation is available on the influence of warm 0301-6226 00 – see front matter  2000 Elsevier Science B.V. All rights reserved. P I I : S 0 3 0 1 - 6 2 2 6 0 0 0 0 1 8 1 - 0 224 D . Rinaldo et al. Livestock Production Science 66 2000 223 –234 conditions on growth performance in pigs, except for using the comparative slaughter method. Data on investigations concerning very high constant ambient body composition of pigs slaughtered at 35 kg live temperatures in the range of 32–358C Holmes, weight and on energy balance are to be presented in 1973; Straub et al., 1976; Campbell and Taverner, another paper. The present one shows data on 1988. Studies on the influence of relative humidity carcass composition of animals killed at 90 kg live on productive traits in pigs are scarce Granier et al., weight. 1998. Therefore, this trial was designed to evaluate For each of the two climatic treatments, i.e. the effects of tropical humid climate and season of tropical climate and controlled environment at 208C the year on voluntary feed intake and growth per- and 75 RH, there were two replicates within each formance of Large White pigs reared in intensive of the two seasons. For each replicate, six litters conditions. were weaned simultaneously at 2862 days of age. Within each litter, four animals, one pair of castrates and one pair of females, were chosen and entered the

2. Materials and methods experimental building. One pig of each pair was