Wednesday, July 6, 2022

Weaning needs to be flexible event

The flurry of activity in the industry relating to schedules, environmental issues, weather extremes and climate change legislation seems to be overtaking the day-to-day issues of adequate feeding and simple planning ahead.

The old adage of concentrating on what you can control rather than sweating on what you cannot, is valid. The case in point is so many farms carrying more lambs over the spring than usual. By now that fact is known so managing the feed supply and planning weaning should be the big focus.

The public expressions on lamb schedule predictions by people with vested interests are getting way too much attention and are more a topic of conversation on farms than making the most of the spring. Not that the sale prices can be ignored in the timing of weaning decision, but just as important is the feed supply, ewe condition, lamb weight gain and the weather predictions. Unfortunately, though, Christmas and ewe shearing too often influence rational weaning decisions. We cannot change Christmas, but I think the shearing policy does not often enough take into account the impact on the timing of weaning. Weaning should be a flexible event determined by the above factors.

I had a fascinating discussion with a budding terminal sire ram breeder who had introduced some French-originated genetics and was measuring some extraordinary suckling lamb growth rates. Extrapolating from the eight-week weights, weaning could be at 90 days with most lambs over 18kg CW. As a terminal sire breeder, should weaning weight of lamb be the major selection target? Given that this is so important for hill-country farmers, it has to be a key selection objective for them. Is that in the interests of the industry at large if we can grow lambs to be ready so early – though most finished lambs are of maternal source, and lambing over New Zealand covers four months. Of course yield and carcase composition are important characteristics as well.

A lot of this is largely academic until we have some semblance of an integrated meat industry. Without this integration there is probably little profit in producing more lambs. Let alone bigger ones.

The intriguing aspect of these suckling lambs growing so fast was where did the extra feed come from for them to do this? Many of them were twins so theoretically they were not getting any more milk than other lambs not growing so fast. Maybe they were just eating more pasture. Of course what every terminal breeder dreams of is that their rams have higher feed conversion efficiency. Not that easy to measure at all but we do know that some breeds or strains of breeds do make significantly more of the feed that they consume than others.

The pasture covers under these ewes and lambs were not limiting intakes. In general we do not get something for nothing so it is probable that these lambs were just capable of consuming more pasture, just like those high-performing dairy cows do. But what does this breed have to offer?

Acknowledging the danger of referring too often to a past experience, the Blonde Aquitaine bulls that I reported on killing out at 420kg CW at one year of age did not appear to eat enough to grow that fast. I did conclude that they had a high feed conversion efficiency.

As is the case every year there are questions about the need to drench suckling lambs and to give them Vitamin B12. The B12 one is relatively easy to answer in that if cobalt levels are very low in the spring then supplementing lambs is justified – but it is unusual for these levels to be low in the spring. The summer yes, but the spring, not often. The trials showing a response are from areas where the levels are really low. Most of NZ does not have such low levels in the spring.

The need to drench suckling lambs is far from easy to answer. If the reason to drench is to take the tapes out, it is easy to answer as there is little evidence that it makes any difference to weaning weights. But these lambs having a roundworm burden that is reducing their weight gain is hard to know. Their faecal egg count does not mean much as their young immune systems allow any worms in them to produce heaps of eggs.

Various trials produce varying results as to the benefit. The common outcome of those trials is, though, that the lambs are cleaner at weaning. So there is no question that that pre-weaning drench does appear to work. I take the approach that if ewes that are lactating well and lambs can access quality pasture then it is unlikely that a drench in them will make a difference.

Take the other extreme of a two-tooth ewe with twins in a spring like is happening this year in the eastern North Island, and there is not much lactation protection for those lambs, a drench is more likely to make a difference. The exception to all of this is the southern South Island where the worm species Nematodirus lurks and can do a lot of damage in some springs. For these, even low faecal egg counts for this worm do indicate a potential problem.

We possibly would think differently about yarding ewes and lambs for this drench if we had some data on the production costs of just that yarding process. From mismothering through to more pneumonia in the summer, there are several ways in which any benefits could be negated.

This drench of lambs is another action which should be the result of a decision process – just like so many others, but so often done as a pure routine with no consideration about the need or cost. 

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