heritability (h²) values related to teat development. Teat length has an h² of 0.46, and teat length is moderately cor- related with daily gain. The same study of nearly 1,000 sows showed an h² for IgG production of 0.35. If a breeding com- pany could start measuring IgG at nucleus level and add it into the breeding index, that would be a major step forward in reducing pre-weaning mortality. Work at Helsinki Univer- sity, Finland, has shown a very good correlation between a handheld digital refractometer and detailed laboratory ELISA tests for IgG concentrations.
Type of farrowing crate In recent years, there has been a move towards a “freedom” type of farrowing pen. That is normally bigger than a normal farrowing pen, with a crate that be opened up after 24 to 72 hours. The suckling behaviour in these freedom pens has been shown to be different from that in traditional farrowing pens. Milk let-down in conventional pens lasted 8.5 seconds as op- posed to 10.3 seconds in the freedom pens. Due to better ac- cess to the teats, there were fewer teat fights in the pens and fewer piglets missed the milk let-downs. More importantly, the piglets that suckled in the pens had a higher weight gain.
Method of cross-fostering The traditional way of cross-fostering was to try to even up the numbers, with maybe a few less on the gilts. When the in- dividual teats are closely observed, the enormous variation in dimension becomes evident. A small 900g piglet will have little chance of obtaining colos- trum from a teat that is 5.0 centimetres long. Similarly, a strong 1.8kg piglet will struggle to cope with very small teats.
When the sows are transferred into farrowing, an assessment should be made of their teat dimensions, large, medium and small. This should ideally be colour-marked onto their farrow- ing cards. The art of cross-fostering is much more successful when carried out by teat dimensions, rather than just by numbers.
How to increase colostrum production Apart from genetic selection as previously mentioned, nutri- tion can play an important part in increasing the quantity and quality of colostrum produced. The inclusion of encapsu- lated medium and short-chain fatty acids in the gestation ra- tion was studied at Queens University, Belfast, Northern Ire- land, UK. At farm level, the treated sows had reduced pre-weaning mortality, and their piglets had increased weaning weights. The detailed analysis of the colostrum showed significantly higher levels of the immunoglobulins IgG and IgM. The treat- ed sows also had greater concentrations of fat and lactose. The concentrations of IgG in the piglets’ serum was studied at two and four weeks of age, and the piglets from treated sows had significantly higher levels of IgG. Medium and short-chain fatty acids do not pass through sow milk. To understand the mechanism, the team in Belfast car- ried out a proteomic evaluation, which is the measure of ex- pression genes through proteins. Basically, there are changes in the milk fat globule membranes. When they are down-reg- ulated, more fat (which contains the immunoglobulins) stays in the milk.
References available on request. ▶PIG PROGRESS | Volume 36, No. 9, 2020 27
When the sows are transferred into farrowing, an assessment should be made of their teat dimensions, large, medium and small.
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