Suppressing the feed intake of finisher pigs: a preliminary study

Manipulation of voluntary feed intake in finisher pigs is potentially a tool for the Australian pork industry to regulate seasonal impacts on finisher pig growth performance and carcass quality, and allow some control over annual pork supply. The general hypothesis tested in this preliminary study was that the strategic use of selected feed ingredients could decrease feed intake in finisher pigs.

A total of 28 individually-housed female pigs (Large White x Landrace) with a starting body weight (BW) of 66.9 ± 0.19 kg (mean ± SD) was used in a randomised complete block design study to examine the effects of several dietary additives (n = 7 pigs per diet) on performance in the finisher period. The diets were: a commercial Control diet [13.8 MJ digestible energy (DE)/kg, 153 g/kg crude protein, 0.59 g available lysine/MJ DE; Reid Stockfeeds, VIC]; Control diet plus 4% CaCl₂+2.2% Na₅P₃O₁₀; Control diet plus chenodeoxycholic acid (CDCA; 120 mg/kg body weight); and Control diet plus 5% lauric acid (LA). Diets 2 and 4 were prepared in 200 kg batches using a cement mixer to incorporate the additives, whereas the CDCA in diet 3 was given as a daily top-dress to the pigs’ feed. Pigs were fed ad libitum for 21 days towards the end of the finisher phase. Water was available on an ad libitum basis. Data were analysed using GLM (Genstat, 15th Edition; UK), and least significant difference (LSD) at α = 0.05 was used to separate treatment means.

There were acceptance issues in pigs offered 4% CaCl₂ + 2.2% Na₅P₃O₁₀ in the first week, so subsequently the inclusion rate was halved for each additive (to 2% CaCl₂ + 1.1% Na₅P₃O₁₀). Overall, ADFI was lowest (P = 0.007) in pigs fed CaCl₂ + Na₅P₃O₁₀ (15% lower than Control pigs) but was not different (P > 0.05) to pigs fed LA, which in turn was similar (P > 0.05) to pigs fed CDCA. This resulted in pigs fed CaCl₂ + Na₅P₃O₁₀ being the lightest (P = 0.039) at the end of the feeding period. Pigs fed LA consumed 10% less feed (P = 0.007) than pigs fed the Control diet, but had similar performance. Pigs fed CDCA or LA showed a better FCR (P = 0.023) relative to pigs fed CaCl₂ + Na₅P₃O₁₀ or the Control diet (an average of 9%) over the 21-day period (Table 1). These data indicate that a reduction in feed intake can be achieved in finisher pigs, with the appetite suppressing effects of CaCl₂ + Na₅P₃O₁₀ possibly working through induction of metabolic acidosis (Yen et al. 1981), and those of LA most likely working through appetite suppression mechanisms such as reduced gastric emptying and (or) increased secretion of appetite-suppressing hormones in the gastrointestinal tract (Little et al. 2007).

Table 1.  The influence of different dietary additives on performance indices in finisher pigs