The response of growing pigs to a choice of diets differing in protein content

Abstract

An experiment was designed to test whether pigs can differentiate between two foods differing in their protein content. A control food (160 g protein per kg food) and six choice-feeding treatments, in which the diets differed only in their protein concentrations, were used in the experiment. Pigs were given the following choices of protein: 220 v. 180; 220 v. 140; 220 v. 100; 180 v. 140; 180 v. 100 and 140 v. 100 g protein per kg food. Group data were collected on 240 Landrace x Large White pigs during the growing phase (30 to 90 kg), all pigs used being of similar genetic background. A 2 x 7 factorial design was replicated twice, with 10 pigs per pen, and with barrows and gilts being penned separately. Food bins for the choice-feeding treatments were placed side-by-side and an 8-day training period, in which the pigs were allowed access to only one of the two foods on alternate days, was used at the beginning of the trial to allow them to learn the position, taste and physiological effect of each of the two foods. All pigs were weighed weekly, as was the amount of food consumed in each pen. The conclusion reached was that growing pigs were able to differentiate successfully between two foods on the basis of their protein content and to change the selected diet to match their changing requirement for dietary protein. As a result, there was a significant reduction in food intake (P < 0-001) and in the P2 backfat thickness (P < 0-01) and the food conversion ratio was significantly improved (P < 0-001) compared with the control treatment.

Human eating behaviour in an evolutionary ecological context

“…It also changes as a consequence of longer-term physiological changes across the lifespan (Kyriazakis et al 1999). With regard to long-term changes, the extent of developmental maturity (Bradford & Gous, 1991;Kyriazakis et al 1993) and pregnancy and lactation (Cooper et al 1994) influence the diet choice of pigs and sheep.…”

Food preferences in farm animals: why don't they always choose wisely?

“…The principle of a training period, in which foods are offered singly in turn to allow the animal to learn to associate a particular set of sensory properties with certain metabolic 'feelings', was introduced by Kyriazakis et al (1990) and this protocol has been adopted by other groups working in the field (Bradford & Gous, 1991;Shariatmadari & Forbes, 1993). Without this enforced training period some animals learn quickly while others eat one food only, or both at random, for many days before suddenly 'discovering' the other food and subsequently selecting an apparently balanced diet ( Fig.…”

Consequences for body composition at farrowing and nutrient partitioning during lactation of a choice-feeding regime during rearing and pregnancy in gilts of different genotypes

“…Consideration has to be given to whether selection against the high CP diet was an aversion either to dietary protein concentration or to Table 6 Pre-feeding plasma insulin (AIU/ml), prolactin (ng/ml) and other metabolite (mmol/l) concentrations and responses of gilts to a glucose challenge on day 14 of lactation a specific dietary component. The concentration of CP in the high protein diet was similar to that used in experiments in which pigs selected substantially higher proportions of the high protein diet (Kyriazakis et al, 1990(Kyriazakis et al, , 1993aBradford and Gous, 1991). Therefore, an aversion to protein per se is unlikely and thus any aversion would seem to be specific to the batch of feed ingredient used.…”

“…A possible reason for the difference between current results and the literature was the age/live weight at which gilts were first exposed to a diet choice. Where pigs of greater than 70 kg have been offered a diet choice, they have usually been exposed to a diet choice from a younger/lighter age and selected initially a higher protein choice which then reduced as time progressed (Bradford and Gous, 1991;Kyriazakis et al, 1993a;Gill et al, 1995). Thus, establishment of a particular diet selection at a younger age would appear to influence continuing choice.…”