Manage a cow's feed and reap long-term rewards
Published 07/12/2011 | 06:00
Some 60pc of total foetal weight gained during pregnancy over is gained in the last 60 days. This makes the dry period unquestionably the most important one in the production cycle of the suckler cow, with nutrition playing a key role. Using body condition scores to monitor cow's feed requirement will have a dynamic effect on calving, fertility, milk production and calf weaning weight. Managing the feeding of the cow rather than just feeding for convenience will therefore pay off for the full year ahead.
At this time, almost all spring calving cows are weaned and probably housed. However, this is a period in the yearly cycle that tends to get neglected despite its importance. The primary focus should be to manage the body condition of the cow with correct feeding. Generally, dry cows weigh in the region of 575kg to 700kg liveweight. This gives the cow a daily requirement of 75MJ/kg of drymatter and a protein content of 8.5pc. Most cows at this stage will have a body condition score of 3-3.5 and it is vital not to build on this condition score during the dry period. If a cow exceeds a condition score of 3.5, it would be preferable to reduce this before calving.
This needs to be simple and also meet the cow's requirements. Most grass silage this year is quite good quality at 9.5-10ME. When fed to appetite, this will usually supply excess energy and protein and therefore increase body condition. Fulfilling the appetite of the cow without over-feeding is difficult where cows are housed and have restricted feed space. Some suggest feeding the cows a number of times per day to avoid bullying and control body condition. This solution is impractical, labour intensive and creates lots of stress for the cows.
When straw is included in the diet of the dry cow it will have a 'fill factor' for the cow. As most straw is low in energy and protein and very fibrous, it will fill the rumen and reduce the appetite of the cow. Chopping and mixing with silage is the ideal method of feeding straw. The amount of feed per cow is directly related to the quality of the silage being fed and the body condition of the pregnant cow. If silage of 10ME is fed then up to 6kg/head/day of straw will be required. This will mean as little as 25kg of silage per head is required to meet all the nutritional requirements of the dry cow while avoiding an increase in body condition.
Wheaten straw is probably the most available straw and can be fed from round or square bales. If the cows are in a bedded house where chopping and mixing isn't an option, then it's best to feed the straw from a round feeder.
Make sure that a good quality mineral or trace element and vitamin supplement is supplied to all dry cows for the full dry cow period and not just the last six weeks before calving. Special attention should be paid to ensuring that calcium contained in the supplement is at a maximum of 3.5pc. There should also be at least 15pc magnesium included to avoid 'downer cows'. Silages with high levels of potassium may require much higher levels of magnesium than is standard in a dry cow mineral, so paying attention to your silage analysis is important.
Gerry Giggins is a livestock nutritionist and can be contacted on firstname.lastname@example.org