November 2014: The importance of interpretation

Big may not necessarily mean best when it comes to piglet performance, despite what a first look at the figures from a feed trial I was looking at recently might suggest. A bit more “digging” can reveal a different message, and one that might lead to revised feeding regimes.

The feed trial data on a large number of post-weaned piglets was designed to determine the most appropriate feeding regime to 15kg and beyond, and the data revealed facts that we’ve known for some time, such as the biggest piglets at weaning would have the greatest advantage in expressing their future genetic potential for growth. This comes with a caveat that the size of the piglet was also related to solid creep feed ingestion during lactation (this having driven digestive maturity).

Pigs are extremely good at self-selecting a ration appropriate for their health, digestive maturity, size and genetic potential, and some of the bigger pigs at weaning simply have not consumed much in the way of creep feed and are as (if not more) vulnerable to the change from maternal milk to the post-weaned starter feed regime. This is further compounded by the fact that groups of piglets can contain small pigs with a developed gut as well as small pigs that are simply underprivileged and extremely vulnerable. The larger piglets in the group can also have the same diversity in digestive requirements.

Many producers still operate a fixed approach to the starter feed regime, such as 2kg of stage one, 3kg of stage two and 4kg of a link diet, feeding a certain number of bags in accordance with the number of pigs in the pen. And this may seem a reasonable approach until you consider the scenarios above. Given the wide range of requirements in a pen, a one-size-fits-all approach may not be best. Indeed, when trialling a feed regime, you can flatter to deceive if the data is not interpreted carefully.

Take the example of a 10kg pig at weaning on a fixed-diet regime that grew at 695g/day over a fixed period and compare this to a 6kg pig on the same regime and in the same time that grew 475g/day. The larger pig appears to perform better, but if you look at DLWG as a function of initial body weight we find the smallest pig was growing 7.9% of its starting weight and the larger pig was growing at 6.95%. This would suggest that the larger pig was compromised in expressing its potential, possibly through having a sub-optimal ration, knocking feed intake and subsequent potential growth rate.

Choice feeding is, therefore, vital in allowing pigs to express their potential, and the bigger the group, the wider the variation in the population and the greater the impact of having different diets would make. My advice is that we need to spend more time finding out what the piglet requires in each situation rather than making assumptions for them.

> Born in Essex, schooled in Suffolk and a graduate of Reading University, Dr Phil Baynes has spent his career in pig welfare and nutrition. Now based in Cheshire, he runs Baynes Nutrition and is a consultant nutritionist to Provimi

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