Eighty-eight commercial, hybrid sows (25% Meishan, 12.5% Duroc and 62.5% Large White x Landrace) were artificially inseminated. Sows were randomly selected and fed the supplemented diets either during the first 60 days of pregnancy (G1) or for 60 days prior to farrowing (G2). Within each group G1 and G2, the sows were allocated to the different dietary treatment groups. The control (C) group was fed with standard pellets. During the experimental period, the remaining sows received standard pellets + 10% energy derived from either (i) excess of the standard diet (E); (ii) palm oil (P); (iii) olive oil (O); (iv) sunflower oil (S); or (v) fish oil (F). During the non-experimental period, all sows received the standard diet only. Litter size (live, dead and mummified) and individual piglet body weights were recorded. On days 0, 35, 56, 84 and 109 of gestation, sows were restrained in a weigh crate whilst their body weight and ultrasonic measurements of backfat thickness were recorded. A glucose tolerance test (GTT) was conducted on day 108 of gestation by administering 0.5 g/kg glucose. Blood samples were taken every 5 to 10 min for 90 min post administration.
No effects were observed in body weight and backfat thickness during gestation due to the experimental diets, however both type and timing of dietary supplementation affected litter size and weight (P<0.05). With the exception of the sunflower oil group, supplementing the maternal diet in G1 resulted in larger and heavier litters, particularly in mothers offered palm oil (P<0.05). Basal blood glucose concentrations tended to be more elevated in G1 than G2 groups, whilst plasma insulin concentrations were similar. Following a GTT, the adjusted area under the curve was greater in G1 compared to G2 sows, despite no differences in glucose clearance were observed. The relationship between glucose curve characteristics following a GTT and litter outcome were directly afected by the maternal diet.
It is concluded that the degree of insulin sensitivity can be altered by both the period during which maternal nutritional supplementation is offered and the fatty acid profile of the diet. Glucose curve characteristics in conjunction with maternal body weight and conformation may be a useful tool to predict total litter performance.
AM Corson, J Laws, JC Litten, PF Dodds, IJ Lean and L Clarke. 2008. Animal, 2 (7): 1045-1054.