Effect of L-glutamine in late gestation sow diets on survivability and growth of piglets

Increased sow prolificacy has led to an increase in pre-weaning mortality in Australia. Reducing pre-weaning mortality would not only have economic benefits for pig producers, but also social and animal welfare benefits. Previous research into the inclusion of L-glutamine in late gestation diets using gilts showed that supplementing gestation diets with 1% L-glutamine between d 90 and 114 of gestation increased average piglet birthweight and significantly reduced variation in piglet birthweight (Wu et al. 2011). The aim of the present study was to see if the inclusion of L-glutamine in late gestation diets fed to multiparous sows under Australian conditions would improve piglet birthweights, and decrease within-litter birthweight variability, therefore improving piglet pre-weaning survival and growth.

At d 80 of gestation, 460 multiparous sows (Parities 1 to 8; Large White x Landrace, PrimeGro™ Genetics, Corowa, NSW, Australia) were allocated to either a commercial gestation diet (n = 218) or the same diet containing L-glutamine (n = 242) at an inclusion rate of 1%. Sows were housed in groups of 40 or 80 and fed a 2.4 kg daily ration via an Electronic Sow Feeder. At 110 days of gestation, sows were transferred to their farrowing accommodation where they remained on their allocated treatment until they farrowed. Live piglets were individually weighed within 24 h of birth and at weaning. A blood sample was obtained from a subset of 427 piglets (Control, n = 216; glutamine, n = 211) within 24 h of birth for analysis of immunoglobulin G (IgG) as an indication of colostrum intake. Piglet mortalities and removals were also recorded. Data were analysed using GLM analysis or a Chi-squared (χ²) test (for piglet survival) (SPSS v24.0, IBM, Armonk, NY, USA). The sow was the experimental unit and data means were analysed by least significant differences (P < 0.05). Sow parity was included in the analysis as a covariate. A coefficient of variation was calculated for each litter in order to measure within litter variation in birth and weaning weight.

There was no difference in the number of piglets born alive between treatments (Table 1). Average birthweight and variation in birthweight of piglets born alive did not differ between treatments, nor did the variation in individual weaning weights. There was a trend for piglets from sows fed the L-glutamine diet to have lower weaning weights than those from sows fed the Control diet (P < 0.10). Piglet survival within the first 24 h after birth was higher for those piglets from sows fed the L-glutamine supplemented diet (95 v. 94%; χ² = 4.05, P = 0.044). However, overall pre-weaning survival was not different between treatments (83.3 v. 82.9%; χ² = 0.13, P = 0.72), for the L-glutamine and Control diet fed sows, respectively. The average 24 h IgG concentration in piglet serum tended to be higher in the piglets from sows fed L-glutamine (21.42 ± 0.66 ng/mL) compared to Control sows (19.69 ± 0.65 ng/mL, P = 0.061).

Table 1.  Litter characteristics of sows fed either a standard Control diet or a diet supplemented with 1% Glutamine from d 80 of gestation until farrowing. Values are means ± s.e.m.

The inclusion of L-glutamine in late gestation diets of multiparous sows did not lead to an improvement in piglet birthweights or overall pre-weaning survival or growth, despite higher 24 h IgG levels in piglets born to those sows fed the L-glutamine diet. Hewitt and van Barneveld (2012) suggest that glutamine levels in Australian sow diets may already be adequate due to the availability and inclusion of animal based protein meals. In conclusion, the addition of L-glutamine sow gestation diets fed to multiparous sows late in gestation in Australia to improve piglet birthweight and pre-weaning survival seems unwarranted.