PHOTO: HERBERT WIGGERMAN
PASTURE ▶▶▶
Grazing behaviour: Why knowing your cows counts
Knowledge of the normal behaviour and daily activities of dairy cows can be useful in two main ways. Firstly, a behaviour change can indicate some fault in management or animal health; secondly, it may be possible to alter and improve the herd routine as a result of studying the pattern of behaviour.
BY DR SALAH ESMAIL, FREELANCE CORRESPONDENT
Cattle preferenc- es may change during the day, such as eating legumes in the morning and grass in the afternoon.
P
art of the art of breeding stock is careful observation of the behaviour of animals so that any abnormal- ities can be detected and remedial action swiftly taken.
Cows on good-quality pasture will walk about 1,600–3,000 m per 24 hours but will walk further, and intake will decline, as the yield of pasture decreases. Intake can be maintained for a time when forage and thus bite size are limited by increased grazing time and the number of bites per minute. However, as grazing time increases, more energy is used for activity and less for production, thus, the minimum grazing time that results in adequate dry matter intake is considered optimum.
It is, therefore, advisable to offer the cows sward with an adequate yield of herbage (about 2,000 kg dry matter per ha) to ensure adequate intake and better performance with minimum distances travelled.
Response to plant maturity If forage is too mature and coarse and low in nutritional val- ue, cattle must spend more time grazing to get the nutrients they need. They may also have to spend a longer time chew- ing to break down this coarser feed for further digestion. At some point, they may not be able to eat enough (and will therefore lose weight) because of the excessive amount of time necessary for chewing. This is when they need more protein supplements to aid digestion and enable them to process the rough feed. It may not be necessary to provide a grain-based supplement, but good-quality alfalfa hay can provide the needed protein.
Effect of pasture size For pastures of the same quality and plant maturity, it was shown that the size of the pasture available to the grazing an- imal will influence its behaviour, particularly the daily dis- tance that it travels. In general, the bigger the area of pasture, the further an animal will walk. Cattle on a 12 ha pasture walked 2.6 km between 4.00am and 8.00pm, whereas similar cattle travelled 4.9 km on a 40 ha pasture during the same period and 8.9 km on a 258 ha pasture. There must be limits to this tendency at each end of the scale, but so far they have not been established.
Forage species Cattle preferences may change during the day, such as eating legumes in the morning and grass in the afternoon. Two the- ories explain this. One is the difference in carbohydrate levels in grass, with more sweetness in the afternoon due to a longer period of photosynthesis and more time to store sug- ars. A second thought is that cattle want something higher in fibre content (i.e. grass rather than legumes) late in the day to maintain more gut fill during the night so that they do not
14 ▶ DAIRY GLOBAL | Volume 9, No. 3, 2022
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