Greedy boars are good for production performance
Sunday, April 5, 2015
Feeding behavior of breeding males correlates well with litter size
and piglet survival
by NORMAN DUNN
Boars "hogging" the trough longer than their pen mates, and consuming more at each feed, can be expected to breed sows with good production performance, according to recent research.
Identifying such correlations between boar behaviour and piglet production represents an important goal because farm animal improvement needs faster ways of predicting potential. After all, waiting for farrowing, and subsequent hog rearing and slaughter results, before judging a breeding boar's full potential represents a huge time lag in the selection procedure.
This is why scientists from the Scottish Agricultural College (SAC) and the breeding company PIC in Germany have been testing boar feeding behaviour and looking for correlations between this and the production of females with big, healthy litters.
The concept seems to be working. A trial noted feeding traits of 2,038 purebred dam line boars and then recorded subsequent breeding performances of female relatives. The males that spent longer than average at the automatic feeder, eating more slowly and consuming more feed per meal, produced gilts with improved production performance. The gilts were direct progeny, but also full or half siblings.
As research group leader Prof. Rainer Roehe of SAC reported in the British Society of Animal Science proceedings: "Genetic correlations indicate that pigs spending a longer time per [feeder] visit, and a longer time per day in the feeder with a lower than average feed intake rate, had relatives with higher genetic potential in litter size."
Also positively associated in this context with the length of time a boar spends feeding is piglet survival, according to Roehe. The professor reckons that this could be an expression of better stress tolerance in the animals. The boar takes its time with feeding and makes sure it is full before leaving the trough, and the related sow is also more laid back when it comes to breeding and caring for her litters.
Dominant sows do best
Research by the University of Giessen in Germany reveals a simple method for identifying the best breeding gilts for retention in the herd.
Where gilts are grouped in pens with automatic feeding points, the social ranking of the young sows is rapidly established and can be recorded. The Giessen researchers decided to follow the breeding history of 890 dominant and not-so-dominant females through to their first farrowing. With 285 breeding females, recording continued right through to their fifth litters.
Earlier research – and practical experience – has indicated that the more dominant females tend to live longer and produce more hogs, a grassroots belief now supported by the Giessen results. For instance, 74 per cent of dominant sows were still in production with their third litters in the survey and 55 per cent farrowed for the fifth time. The respective percentages for the non-dominant animals in the trial were 61 and 42. Lifetime piglet production for all sows recorded to their third farrowing proved 11 per cent higher for the dominant sows and, at fifth farrowing, 15 per cent more.
At the gilt stage, the animals were penned in groups of 35 and automatically classified for dominance through their transponders triggering their place in the feeding queue over a period of weeks. Service success rate for the dominant gilts (96.8 per cent) was better than the non-dominant result of 92.6 per cent.
Naturally, not every breeding unit has electronic identification of animals for feeding. But wherever loose housing is possible, a good idea of group hierarchy can be rapidly determined as an additional aid in choosing herd replacements.
Too-thin sows increase the piglet death toll
What are the main reasons for stillborn piglets? Every hog producer has a personal list of causes. But experience shows us that a drawn-out farrowing operation certainly increases the death rate. There's also a firm belief that gilts starting with a higher per centage of stillborn piglets at first farrowing tend to continue with above-average piglet deaths for the rest of their productive lives. A sow in poor body condition? Especially here, more dead or dying piglets can be expected.
Work at Denmark's Pig Research Centre confirms this negative effect from too-thin sows. The research results also support the notion that the national piglet stillborn figure, at around 12 per cent and representing almost half all litter losses up to weaning, can be reduced through selection of sows. The scientists involved feel, though, that heritability here is fairly low.
Work ongoing at the centre looks for more direct ways of influencing this type of litter loss. Starting in 2012, six commercial farms were surveyed. Every litter was monitored and stillborn piglets taken away for post-mortem examination. Results so far reveal that up to 91 per cent of the piglets born dead or dying were still alive and vital in the uterus when the birth process began. And seven to 34 per cent were still alive at point of birth. Conclusion: supervision of farrowing sows below average condition should be part of the herd routine. The Danish survey also shows that the second litter is where most stillborn losses occur with thin sows – yet another pointer urging attendance at farrowing.
So far, no silver bullet for reducing these deaths is offered by the Danish work, just the time-proven approach of keeping breeding sows in good condition and identifying the possible problem breeders for extra attention at farrowing.
Crates versus free-farrowing: a draw so far?
One argument used by fans of free-farrowing systems is that the birth process tends to be faster where the sow is left to lie how she wants in the pen. And the speedier the farrowing, the higher the survival chances for weaker litter members.
Now come results from the Danish Pig Research Centre that indicate very little difference in total average farrowing time between free-farrowing and crates. In fact, on average performance with 123-recorded farrowings, the crated sows took 390 minutes for the entire process, about half an hour less than the mean time recorded for the loose-housed animals.
Variation within the two classes was considerable, however, with crated sows taking from 264 minutes to 646 minutes. The longest farrowing for the loose sows in the trial was 583 minutes. And the time taken for individual piglet births was indeed longer on average for crated sows at 188 minutes compared with 168 minutes.
Average total litter size (total born) in the survey was 18.4 per farrowing.
Slow-grown pork not the answer
Slow food can be a good thing. But Caroline Mitchell doesn't agree with slow-grown pork. This food specialist believes the claim that hogs produce better meat when raised slowly with a longer time from birth to slaughter is misleading. In fact, it's important to exploit the full genetic potential for weight gain if the resultant meat is to remain tender, she points out. An interrupted growth curve usually means a tough chew up ahead for consumers.
The problem with branded pork products is that, if taste and texture don't match up to expectations or claims, then that particular brand is not bought again.
Caroline Mitchell is Meat Science Director with international breeding company JSR Genetics. Her message to hog rearers nowadays is that more thought has to be given to the taste experience, even back on the farm. Feeding to genetic growth potential is an example where farmers have at least some influence.
Another is proper fasting periods before slaughter. Unattractive dark, firm and dry (DFD) meat is often a result of too short, or too long, fasting. Between 14 and 18 hours is a good target. She admits hog producers have rather less control over another cause of DFD meat: long waiting periods at the slaughterhouse.
There are still European processors who claim that overnighting the hogs on the premises leaves them time to calm down after transport and helps reduce stress. Mitchell replies that overnight lairage is definitely to be avoided. "Load on time. Keep the delivery slot. Help keep lairage down to around three hours," is her advice.
She also puts her finger on one of the great mysteries of modern pork production: Who decided that the consumer wanted ultra-lean pork products in the first place? "We know that fat improves flavour, yet the last 25 years have been spent selecting against it." Here, the hog producer has very little say in the matter although, thankfully, the main breeding companies increasingly offer lines with more intramuscular fat.
Pork brand labelling should be focusing on eating quality and not so much on perceived ethical advantages, concludes Mitchell. For instance it's wrong, she suggests, to send out the message that meat from outdoor-bred animals is better than that from indoor ones or that rare breed pork is better than meat from modern swine lines. Quality meat with taste is the target. Marketing messages should never confuse the issue. BP