Farm Ireland

Tuesday 24 October 2017

Milk decline in stressed herds

Dr Daniel Ryan

THE PAST month has brought about a drastic change in weather with high rainfall and a rapid increase in grass re-growth rates.

Many farmers faced a no grass situation in early July as the dry weather in May and June reduced grass growth rates and prevented uptake of applied fertilisers. Many farmers introduced silage and/or increased concentrate supplementations to avoid significant drops in milk production and reproductive performance.

Grass re-growth rates were rapid in the past three weeks. However, a consequent impact was a rapid uptake of fertilisers previously applied, which could not be absorbed during drought conditions in June. These grass re-growths are high in protein. This has resulted in cows scouring as they consume more water in the process of getting rid of excessive protein. Cows lose body condition score in this situation. We have many cases of significant milk drops when cows have experienced this scenario. Any milk drops greater than 0.25 litres/cow/day is a sign of stress on the herd. This will ultimately decrease pregnancy rate to services.

This can be avoided by ensuring the supplementation of a high energy concentrate. Some farmers have introduced good-quality silage as a buffer feed. The secret here is to supply extra energy to address the demands imposed by excessive grass proteins.

Phosphorus deficiency has been diagnosed on several farms. One of the signs associated with this phenomenon is an increased incidence of cows eating clay or stones. This should not be confused with a similar scenario when rumen function was disturbed in cows during May when there was a flush of grass with low fibre intakes. In this case, butterfat percentages dropped close to or below protein percentages. Due to insufficient fibre intake, cows ate stones to satisfy a craving.

Grassland management entails supply of both quantity and quality, which is difficult under Irish climatic conditions. Greater consideration has to be given to buffer feeding of cows to maintain rumen health and thereby overall cow wellbeing.

The demand for scanning of dairy herds before the breeding season finishes has been unprecedented. Farmers need to get a picture of calving patterns next spring and to address cows presumed pregnant and not pregnant after scanning.

At present we are identifying 10-20pc of the herd presumed pregnant as not being pregnant. Cows bred now will calve in May 2011. This is far from ideal. There has been an impact of two previous difficult grazing seasons on reproductive performance. The number of cows calving in April and May has increased with a knock-on effect on the next breeding season.

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In conclusion, diet management, in association with body condition score maintenance, is essential if compact calving is to be achieved in a grass-based milk production system.

Irish Independent