Piglets born with low birthweights (LBiW) are likely to be lighter at weaning, according to S.L. Douglas of Newcastle University in the UK and co-authors there and with Primary Diets, part of AB Agri.

In a paper in Journal of Animal Science, they explain that starter regimes tailored for pigs of average bodyweight therefore may not be optimal for LBiW nursery performance.

Their objective was to determine if LBiW pigs benefit from a high specification starter regime and the provision of extra feed (additional allowance of last phase diet of the starter regime) in comparison to a standard commercial regime.

Additionally, the effect of starter regime on performance of normal birth weight (NBiW) pigs at weaning was determined and compared to that of LBiW pigs.

Finally, the cost effectiveness of the treatments was determined.

The experiment was therefore an incomplete 2×2×2 factorial design, as the provision of extra feed was given only to LBiW pigs (n=6 replicates per treatment; five pigs per replicate).

Treatments comprised birthweight (LBiW or NBiW), starter regime (high specification [HS] or standard starter [SS]), and extra feed 3 quantity (yes [YF] or no [NF], for LBiW pigs only; feed 3 corresponded to the last phase diet of the starter regime).

At weaning (day 28), pigs were randomly assigned within each birthweight category to treatment groups.

Nutritional treatments were fed ad libitum on a kilogram-per-head basis for approximately three weeks, followed by a common weaner diet fed ad libitum until day 70.

Starter regime (P = 0.019), feed 3 amount (P=0.010), and their interaction (P=0.029) had an effect on average daily gain of LBiW pigs from days 28 to 49, with pigs on HS followed by YF (HY) performing best.

An improvement in feed conversion ratio was noted between days 28 and 49 for pigs fed the additional feed 3 (P=0.030); between days 49 and 70, the only residual effect seen was of starter regime (P=0.017) on average daily gain.

In contrast, there was no significant effect of starter regime from days 28 to 70 on average daily gain, average daily feed intake or feed conversion ratio of NBiW pigs.

By days 49 and 70, LBiW pigs on regime HY weighed the same as NBiW pigs (day 70 bodyweight; 30.0 versus 30.6kg; P=0.413), with similar growth rates from days 28 to 70 (0.570 versus 0.533kg per day; P=0.137).

Despite highest feed cost for regime HY at US$12.30 per pig, its margin over feed was greatest ($23.40). Conversely, regime SS gave the best margin over feed for NBiW pigs at $22.70 per pig.

Douglas and co-authors concluded that a post-weaning feeding regime formulated for LBiW pigs improved the average daily gain and feed conversion ratio to the end of the nursery phase, enabling them to achieve the same weight as NBiW.

They added that targeting the provision of the high-quality expensive regime only to light pigs will ensure maximum growth and increased profitability.

Reference

Douglas S.L., I. Wellock, S.A. Edwards and I. Kyriazakis. 2014. High specification starter diets improve the performance of low birth weight pigs to 10 weeks of age. J. Anim. Sci. 92:4741-4750. doi: 10.2527/jas.2014-7625

October 2014