A way to balance out litter size and milk availability

Thursday, April 3, 2014

Recent Swedish research suggests that cross-suckling helps females retain body condition and weight, and that cross-suckling piglets do slightly better than those that stick with their natural mothers

by NORMAN DUNN

Cross-suckling litters with groups of nursing sows is popular throughout Europe in organically managed herds, according to the Swedish University of Agricultural Sciences (SLU). Researchers there also note a small and growing section of conventional hog producers taking this approach.

Terhi Alanko at the SLU finds nursing sows that allow cross-suckling seem to retain body condition and weight better than females that have only their own litters suckling. Cross-suckling piglets also seem to do slightly better than those that stick with their natural mothers throughout the nursing period, according to Alanko's latest work.

This researcher recorded a group of 40 Landrace x Yorkshire sows through four consecutive breeding cycles in a cross-suckling system to find out more about the pros and cons involved. The sows were served with Hampshire semen and weaning took place at seven weeks. (This long nursing period is a stipulation for the Swedish KRAV welfare pork label. Normally, weaning is at a minimum four weeks under Swedish law.) The sows farrowed in single pens and stayed there for two weeks before joining a group of four to five sows in straw-bedded pens measuring a maximum 114 square metres with a single feeder and two to three water nipples.

Researcher Alanko first confirms that, even in nursing groups, there are sows that just don't allow stranger piglets to suckle them, although this behaviour could, she finds, differ for the same sows from one farrowing to the next. With the piglets themselves, the results indicate that they're not so fussy, straying from their mother the minute it appears they'll get more milk elsewhere. From his group of 40 sows, just under half were allowing all comers to suckle when recorded in the fourth week of lactation. This proportion had dwindled to one third of the sows by the last week before weaning. On the whole, the sows allowing cross-suckling had smaller litters with one piglet less on average.

Comparing results between those allowing cross-suckling and the others indicated slight advantages in almost every count for cross-suckling. For instance, these sows retained good body condition with 0.1 millimetres more backfat thickness at week four into the lactation and weighing an average four kilograms extra. By week six, the bodyweight advantage had dropped to two kilograms, although backfat had increased to an average 0.3 millimetres. Piglet daily liveweight gain was just about the same at 397 to 398 grams, mortality too at from two to 3.4 per cent.

No recommendations have sprung from this latest piece of research into cross-suckling. But the results do underline that sows in better condition with smaller litters are likely to allow cross-suckling and that all piglets on average seem to benefit from the strategy. All-in-all, for smaller units anyway, this approach seems to offer a natural way of balancing out different litter sizes and milk availability.

Benchmarking with a solid base
One of the experts that helped establish the two tons of pork per sow annual production target in Europe is launching another attractive output indicator for swine farmers: "Hogs weaned per farrowing place."

Dr. Grant Walling, director of science and technology with multinational breeding company JSR Genetics, has kept the industry humming with similar concrete calculation bases for swine profitability over the years, a talent ensuring him many mentions in these pages. His latest Key Performance Indicator (KPI) quite rightly guides us firmly away from the purely physical performance benchmarks that are so popular – KPIs such as numbers weaned per sow each year or piglet mortality as a percentage of litter. These are good indicators of stock management, but don't tell us much about unit profitability, cautions Dr. Walling.

He adds that when everything is boiled down to benchmarking returns for a particular herd, then a really concrete base is needed. For instance, percentage piglet mortality per litter depends on the size of the litter left alive on day 1. And weaners per sow per year can be manipulated by adjusting the times when a sow joins the breeding herd.

A measure used increasingly in big Russian herds, on the other hand, is number of pigs weaned per farrowing place. There can be no doubt, points out Dr. Walling, about the number of actual farrowing places, nor about the amount of weaners "sold" on to the feeding unit.

While the purely physical benchmarks certainly retain their important place in management recording, this last KPI encourages tighter management to make sure as many as possible of the available farrowing places are filled. It is also a reliable measure of return on capital expenditure on buildings – figures that bank managers, as well as farm managers, are always very keen to appraise.

Only heaviest piglets do well on milk replacer
Piglets taken out of the litter in the first days of life and fed milk replacer instead of mothers' milk can perform just as well as their mates left at the udder, but they need to be amongst the fittest and heaviest of the family to start with. This is the message from a 250-piglet, birth-to-slaughter trial at the German Haus Düsse Agricultural Centre in Westphalia. With the size of litters nowadays, piglet producers are finding it hard to have enough natural foster mothers at hand to help reduce numbers at individual udders. Haus Düsse set out to find the effects of substituting foster sows with milk/feed dispensers in this respect.

Four groups were recorded. One featured piglets with birth weights of between one to 1.5 kilograms taken from their mothers and set in pens with milk/feed dispensers, while a second took the same course with birth weights of 1.5 kilograms and more. Acting as control were two groups left with their mothers.  

Both groups of removed piglets were put into pens with dispensers offering ad lib milk replacer for their first 10 days of life, at which time pre-starter rations were also put on offer. The naturally nursed piglets were also offered ad lib milk replacer in troughs up to day 14 with pre-starter thereafter. Suckling and milk replacer supplies were stopped for all groups on day 27.

At penning for the growing phase, the piglets that had stayed with mother were the heaviest at 29.4 kilograms (one to 1.5 kilograms birth weight) and 31.6 kilograms (1.50 kilograms and more), although the over 1.5 kilogram birth weight animals fed by dispenser weren't far behind, at 28.2 kilograms. The lighter feed dispenser piglets were further down the scale at 25.1 kilograms.

Through to slaughter at 120 to 122 kilograms liveweight, the heavier feed dispenser group actually overtook the lighter naturally nursed group in daily liveweight gain and in terms of margin over feed and housing costs.

Conclusion: milk replacer and pre-starter via dispenser can profitably take over from a mother or foster sow for those extra piglets – but the solution only really pays with the heaviest litter members. BP