Thirty sows were allocated at their first farrowing to five litter size treatments. Litter sizes of six, eight, 10,12 and 14 were established by cross-fostering within 48 h post partum. Milk yield (Y, kg/day) of sows was linearly related to litter size (L) and was described by the equations; Y = 5-98 (s.e. 0-48) + 0-689 (s.e. 0-046)L, R 2 = 0-99; residual s.d. = 0-29; P < 0-001 and Y = 8-20 (s.e. 0-46) + 0-324 (s.e. 0-044)1, R 2 = 0-95; residual s.d. = 0-28; P < 0-002 for early (day 10 to day 14) and late (day 24 to day 28) lactation, respectively. The composition of milk from sows suckling various litter sizes remained relatively stable but suckling frequency in early lactation increased linearly in response to increased litter size. Litter size significantly affected the average growth rate of individual piglets; piglet growth rate from birth to weaning at 28 days of age decreased from 283 giday to 202 giday in response to increasing litter size from six to 14. The relationships between milk yield, average piglet growth rate and litter size indicate that the number of functional glands is the major factor influencing milk yield of sows. Increasing the number of functional glands by increasing litter size more than compensates for any decrease in milk output from individual glands.

No abstract

Thirty-two male pigs were used to investigate the effects of nine levels of dietary lysine ranging from 0-41 to 1-30 g lysine per MJ gross energy (GE) on the performance of pigs weaned at 1 to 2 days of age and growing between 2 and 7 kg live weight. The nine dietary lysine treatments, which contained similar levels of GE and balance of essential amino acids, were offered to the pigs at a common feeding level of 2-0 MJ GE per kg metabolic live weight (M 075 ) per day. Growth performance and protein deposition rates increased linearly with increasing dietary lysine content up to about 0-97 g lysine per MJ GE and remained relatively constant thereafter. The response of protein deposition (PD, g/day) in the whole body of pigs to dietary lysine (L, g lysine per MJ GE) was described by three models. The respective regression equation for the quadratic function was PD = -14-23 + 87-66 L -36-00 L 2 and maximum protein deposition occurred at 1-22 g lysine per MJ GE. The rectilinear model, which had an ascending linear phase (PD = 1-49 + 40-10 L, R 2 = 0-98, P < 0-001) and a horizontal component representing a mean protein deposition rate of 39-7g/day revealed that maximum protein deposition occurred at 0-95g lysine per MJ GE. Finally, application of the asymptotic model also revealed a highly significant equation: PD = 43-40 -79-99 X 0-0711 1 , R 2 = 0-94, P < 0-001; which indicates a dietary requirement of 1-07 g lysine per MJ GE assuming that the dietary requirement was estimated at 0-90 of the asymptote maximal value. The results indicate that the dietary lysine requirement for pigs during the first 3 weeks of life appears to have changed little over the past 20 years despite substantial changes in genotype.

Eighteen individually housed boars were randomly allocated to one of three dietary treatments, an experimental wheat diet containing 989.4 g kg −1 of a basal wheat diet, or this experimental wheat diet with 500 g kg −1 of the basal wheat diet replaced with 500 g kg −1 of either transgenic or non-transgenic peas. The transgenic peas expressed the bean (Phaseolus vulgaris L.) α-amylase inhibitor 1 gene. Diets contained n-hexatriacontane (0.2 g kg −1 ) as an indigestible marker to allow the determination of nutrient digestibility at the terminal ileum. Pigs were offered 1.6 kg day −1 for 15 days, after which they were anaesthetised, the ileal and faecal digesta collected and the pigs subsequently euthanased. The ileal dry matter and starch digestibilities of the experimental wheat, non-transgenic and transgenic pea diets were 78.3, 74.2 and 45.8% and 95.9, 95.2 and 42.4%, respectively. The apparent nutrient digestibilities of the non-transgenic and transgenic peas were determined by difference. The ileal dry matter digestibility was significantly reduced in the transgenic peas compared with the non-transgenic peas (12.7 and 69.9%, respectively; P = 0.006), which was largely due to a reduced starch digestibility. The apparent crude protein digestibilities of the transgenic peas were similar to the non-transgenic, being 79.7 and 78.5%, respectively. The amino acid digestibilities of the transgenic and non-transgenic peas were also similar.

In a 4 x 2 factorial experiment, 672 White Leghorn hens were given diets with four levels (0, 10,20 and 40 g kg-I) of sunflower seeds and two levels (7.0 and 8.0 g kg-I) of dietary lysine from 43 to 67 weeks of age. The inclusion of increasing levels of sunflower seeds in the diet increased (P