Interrelationships between dietary ractopamine,energy intake, and sex in pigs

Abstract

A major constraint to protein deposition in the pig is energy intake. Ractopamine (RAC) isa b-agonist which has been shown to increase protein deposition under both ad libitum and restrictive feeding regimes. To assess the interactions between energy intake, sex, and dietary RAC, 104 crossbred pigs (52 boars and 52 gilts) were used in a slaughter-balance experiment conducted over the growth phase of 60-90 kg liveweight. To obtain initial body composition, 4 pigs of each sex were slaughtered at 60 kg. The remaining 96 pigs were allocated to a 2 6 2 factorial experiment. The respective factors were sex (boar or gilt), dietary digestible energy (DE) intake (21·2, 24·7, 28·2, 32·7, 36·7MJ DE/day and ad libitum), and dietary RAC (0 and 20 mg/kg of ractopamine.HCl). Average daily gain increased with DE intake and was faster for boars than gilts. Dietary RAC increased averagedaily gain in both boars and gilts independent of DE intake. Neither dietary RAC nor sex had any effect on ad libitum feed intakes while effects on feed : gain ratio reciprocated growth rates. Protein deposition increased with DE intake and was higher in boars than in gilts. Although protein deposition was increased by dietary RAC in both boars and gilts across the range of DE intakes investigated,ad libitum feed intakes were necessary to maximise protein deposition. Fat deposition increased with DE intake and was greater in gilts than in boars. Whereas dietary RAC had no effect on the rateof fat deposition or backfat depths, the fat content of the empty body was lower due to increased protein deposition and lower fat : protein ratio. Dietary RAC improves growth performance and carcass composition in both boars and gilts independent of DE intake. However, ad libitum feed intakes maybe necessary if responses are to be maximised.

The effect of immunization against GnRF on nutrient requirements of male pigs: a review

“…The studies that have shown no difference in lysine requirement have often been conducted with individually penned pigs where the full feed intake potential can be expressed and sometimes, in these cases, entire males may consume more feed than gilts (Dunshea et al, 1998;King et al, 2004). However, in commercial conditions, the ad libitum feed intake of entire males is well below that seen when entire males are penned in individual pens and slightly less than gilts (Dunshea, 2005).…”

“…The slope of the relationship between energy intake and protein deposition is steeper for entire males than for gilts or barrows (Campbell et al, 1985;Quiniou et al, 1996;Dunshea et al, 1998;King et al, 2004). Although older data suggest that, in finisher pigs, a plateau in protein deposition was achieved in all genders at an intake of around 33 to 42 MJ DE/day (Campbell et al, 1985;, studies conducted with genetically improved pigs suggest that the plateau occurs at higher feed intakes or, in the case of elite entire males, not at all (Rao and McKracken 1992;Dunshea et al, 1998;King et al, 2004).…”

“…In heavier pigs (60 to 100 kg BW), these authors found the lysine requirement (g/kg) was slightly higher in entire males than in gilts in one study but not in two others (O'Connell et al, 2006). However, in the most recent studies conducted with high-performing grower pigs, it was found that the lysine requirement of entire males was higher than that of gilts (Quiniou et al, 2010;Moore et al, 2012;Rikard-Bell et al, 2012).The studies that have shown no difference in lysine requirement have often been conducted with individually penned pigs where the full feed intake potential can be expressed and sometimes, in these cases, entire males may consume more feed than gilts (Dunshea et al, 1998;King et al, 2004). However, in commercial conditions, the ad libitum feed intake of entire males is well below that seen when entire males are penned in individual pens and slightly less than gilts (Dunshea, 2005).…”

Energia líquida e ractopamina para leitoas em terminação sob altas temperaturas ambientais

“…Este resultado está de acordo com DUNSHEA et al (1998) que não constataram interação entre níveis de energia digestível (21,2; 24,7; 28,2; 32,7; 36,7MJ dia -1 e a vontade) e a inclusão de 20ppm de ractopamina sobre o desempenho de suínos em terminação.…”

Growth and development of offspring following supplementation of sow diets with oil during early to mid gestation

“…It is well established that the fatty acid composition of body fat reserves reflects that of the diet (Huo et al, 2003), and that fat deposition, in both pregnant and non-pregnant animals, is increased with increasing energy intake (Dunshea et al, 1998;Revell et al, 1998). Since maternal fat reserves are mobilised during late gestation and lactation (Mullan and Williams, 1990;Whittemore, 1998;Trottier and Johnston, 2001), it seems probable that the fatty acid composition of maternal fat reserves may have consequences for piglet growth and survival (Cieslak et al, 1983;Rooke et al, 2001b and c).…”