On July 31, just before the start of calving, all cows were weighed and condition scored. The results recorded were an average liveweight of 441kg and an average condition score (BCS) of 5.3 for the low-input herd, compared with 463kg and 5.5 for the intensive herd.
These figures compare favourably with those recorded on May 27, when all the cows were dried off and settled into their winter management regimes. Figures recorded then were 398kg and 4.6 BCS for the low-input herd and 414kg and 4.9 BCS for the intensive herd.
There have been significant winter gains from both herds and these gains are reasonably similar, 43kg and 0.7 BCS for the low-input herd and 49kg and 0.6 BCS for the intensive herd. It could be fairly easy to write off the weight gain figures as a result of the growth and development of the foetal calf. Not so, despite the fact that these gains will be significant.
These are mixed-age Jersey cows so calf birthweights would probably be about 30kg. Double that to allow for the uterine fluids, placenta and other material and just before calving the true body weight could be about 60kg less than measured.
‘The rule of thumb on the inability to put condition on cows after June will have the exceptions. The question then must be how? Or why?’
That might appear to be in the same ballpark but some of those cows will not be calving until the end of September. Probably more significantly, a fair amount of the weight recorded at the end of May would have been foetal material. So it would be safe to assume that a reasonable proportion of the June and July weight gains would have been genuine.
This would be reinforced by the fact that condition score increased over the same time. Condition scoring is meant to ignore pregnancy status.
This data shows both herds were in satisfactory condition going into calving, and visual observation at the beginning of August would have confirmed this. The generally accepted target of 5.0 minimum condition score at calving was comfortably met. A nit-picking critic could say too much, the argument being that if 5.0 BCS is the target then exceeding it excessively must indicate that feed has been used to lay down unnecessary fat.
This argument quickly loses validity when it is remembered that the BCS 5.0 target applies to the individual cow, not the herd average. Any cow starting the season at less than 5.0 BCS is already on the back foot.
Simplistically, a herd with all cows calving at BCS 5.0 will out-perform one with half the cows calving at BCS 5.5 and the other half at 4.5, even though their average BCS is the same.
The good condition score achieved at calving is even more pleasing when it is noted that these were below the 5.0 mark at the end of May. I have always followed the rule of thumb that it’s extremely difficult to put condition on cows after June 1. I have generally recommended along the lines of “work hard to get all cows to BCS 5.0 by June 1 but if you don’t make it stop trying, because if you don’t, you won’t achieve it anyway, and all you will do is waste valuable winter feed”. The worst thing you can do is, some time in July, wake up to the fact you’re not going to make it and start pumping valuable winter feed into the cow in an attempt to meet the target. Unfortunately, in late pregnancy the foetal calf has been described as an almost perfect little parasite, meaning most extra feeding will go to the developing calf.
I suggested the most inefficient way of gaining an income from feeding livestock is to feed costly winter feed to late pregnancy cows when the only economic gain will be a few extra kilograms on the bobby calf, and then there’s the potential negative effect of calving difficulties.
‘It will be difficult to get above-maintenance feed levels into cows under wet conditions and any increments that are achieved will be burnt up by the increased maintenance requirements brought about by the cold, wet conditions.’
The rule of thumb on the inability to put condition on cows after June will have the exceptions. The question then must be how? Or why?
After many years observing winter dairy farm management I can confidently say what will enable cows to gain condition over this period is a dry winter.
This was certainly the case at Stratford this year, with June rainfall recorded at 112mm compared with an average of 203mm, and July rainfall being 87mm against an average of 221mm.
So that’s the how – now for the why.
I have referred in the past to work done at the old Taranaki Agricultural Research Station, showing that under extremely wet weather conditions, up to 80% of feed offered can be trodden into the ground. Even under moderately soft and moist conditions it can still be 20%.
Now let’s look at the cows’ winter grazing pattern. We know that a good solid grazing for three hours will provide a cow with her daily maintenance requirement. We also know that after about three hours a cow will generally take a break from grazing, because of grazing fatigue and a sated appetite. It’s not the standing still and grazing that does the treading damage but rather the moving around. This means that utilisation will be fairly good in the first three hours, even under wet conditions. If a cow has been offered only a maintenance feed level, utilisation percentage will be good, but past the three-hour period treading will have an increased effect.
What happens when above-maintenance feed levels are offered?
Under wet conditions the cow’s intake drops off after three hours. The cow tends to wander, probably picking at the odd bit of grass. Under wet, cold conditions she will seek shelter and quite probably play musical chairs with her mates, resulting in more movement. The result is that most of the feed left after the three hours’ grazing will be trodden in. This wastage will be exponential – the more extra feed offered the greater the proportional loss.
‘Work hard to get all cows to BCS 5.0 by June 1 but if you don’t make it stop trying, because if you don’t, you won’t achieve it anyway, and all you will do is waste valuable winter feed.’
It will be difficult to get above-maintenance feed levels into cows under wet conditions and any increments that are achieved will be burnt up by the increased maintenance requirements brought about by the cold, wet conditions.
In dry conditions, when fed to above-maintenance levels, after three hours the cow will still not do too much treading damage. On dry ground she will spend much more time lying down. When appetite has been recharged, feed will still be available and this, combined with lower maintenance requirements, will translate to condition gain.
Greater condition gain was made by the intensive group which had the big advantage of indoor resting and feeding. With these facilities available the rule has to be revised to, “No condition gain over winter when paddock grazing only”. In the previous two seasons significant winter condition gain was obtained for the intensive herd with the indoor feeding facility, but not with the outdoor, low-input, group.
The lesson must be that if a condition gain over winter is to be attempted, only feed above maintenance when the ground is firm.
