Extract from a transcript from the San Jolly Sheep Nutrition Day
San Jolly presented at a Sheep Nutrition Day held by the BCG on 29 July 2005.
Below is a modified extract from a transcript of San's presentation.
The full transcript of the day is available for purchase (cost: $15) from the BCG Office (03 5492 2787).
One of the hazards of winter pastures is there is not enough dry matter on offer. If you are lambing onto these sorts of pastures at the moment, there are huge implications for early rumen development in these lambs. The rumen development that lambs undergo in their first 85 days of life sets them up for life. So, if you are lambing at the moment the next three months are critical for lamb nutrition.
Another issue at the moment is that pastures can be excessively high in protein. Early grass dominant pastures can be as high as 30 percent protein and early medic pastures can be as high as 35-40 percent. The reality is that ewes only need about 14-15 percent protein whether they are in late pregnancy or early lactation.
The result is that when ewes are eating pastures that are up around 30-40 percent protein, the ewe will only utilise 14-15 percent of that protein; the rest gets converted to ammonia in the rumen, sent off to the liver, converted to urea, and excreted back out on to the pasture. This is a highly energy-expensive process, and that is energy that the ewe needs to maintain herself. The energy levels in these pastures is actually quite high – it’s about 12.5 ME – it’s just that they can’t get enough of it.
In native pastures, which most cropping people tend to call weeds, the protein level is not nearly as high. Also if you set aside some cropping paddocks for early feed, the protein levels are also not so high.
Low levels of effective fibre is also a hazard of winter pastures. One of the things that sheep thrive on is their rumen receiving fibre, because the whole thing about sheep productivity is having a healthy rumen. If the rumen doesn’t get any fibre, there is nothing stimulating and tickling the little rumen papillae to make it contract. And a rumen that is sitting around not doing much produces a really sick sheep. So what you tend to get also on pasture-based systems, even when there is enough pasture around, is a drop in rumen pH anyway, physiologically, on any pasture-based system, because in winter it tends to be low in fibre.
The other compounding factor that can occur once you get into late winter, are mineral deficiencies. As the feed starts to grow, that’s when these animals tend to get the problems with mineral deficiencies, if you have got any inherent deficiencies on your place.
So you can see that whether you have got a reasonable season or a dreadful season, in winter generally, sheep are really up against it, especially highly productive sheep like pregnant ewes or ewes with twins.
So the main way to overcome this is to set them up at the end of this year when you are weaning the lambs and make sure you get them back into condition score 3 ASAP. Give them priority use of the stubbles straight after the header comes out. Get that condition back on quickly and then it is cheaper and easier to maintain them over the summer and autumn, rather than suddenly in late autumn having to increase and increase and increase the amount of grain. Most nutrients fed in the last four to six weeks of pregnancy are diverted to the lamb So it’s all too late at this time for the ewe. The time to set it up is at the end of the year.