Ground breaking research on feed and milk quality in goats

Janne Karin Brodin

It is an express wish that Norwegian goat’s milk be produced based on Norwegian local feed resources. In her research, PhD student Ingjerd Dønnem has shown that goats have a great capacity for utilizing winter feed based on Norwegian grasses.

When the grass and clover was harvested far earlier than normal, the goats ate a large amount of silage, and were less dependent on concentrates to achieve a high milk yield.

Ingjerd Dønnem Photo: Janne Brodin

The largest number of Norwegian dairy goats is to be found in Troms, in the rural communities of the Western fiords and in mountain settlements in the Eastern part of the country. In the winter, the staple feed for goats is grass silage, and in summer they mostly feed off rough grazing lands. The quality of the milk varies, and significant quantities of the milk have been of too poor quality to use for making white goat cheeses.

Extensive and intensive feeding of goats
The goat is well known for its ability to utilize uncultivated lands, where it not only feeds on grass but on bushes and trees. In this way, it helps prevent cultural and natural landscapes from growing over. Dønnem’s work has shown that the goat also efficiently uses more concentrated feedstuffs from Norwegian farming. When the silage is harvested early, well preserved and finely sliced, the goats eat at least as much, body weight taken into account, as our high yielding dairy cows.

Milk quality
Off-flavours in milk due to high concentrations of free fatty acids are a well known problem in dairy cow as well as in goat milk production. In cow’s milk, this occurs especially when the animal’s energy is low and it needs to draw on its body fat reserves. One of Dønnem’s hypotheses was that this was also true for goats, and that a high energy uptake from high quality silage would reduce the problem of the high free fatty acid content of the milk.

Surprising results
Quite to the contrary, it turned out that a high feed uptake, positive energy balance and the ability to deposit body fat in fact increased the problem of off-flavours in goat’s milk. The best milk was produced by goats having a lower feed uptake, and who produced milk partly based on energy from mobilized body fat. Neither did generous feeding through the winter and spring reduce the problem at mountain pasture the following summer. In fact, quite the opposite seemed to be the case. This doctoral work did, however, point to the benefit of the goats being in good body condition at kidding, so as to have sufficient amounts of body fat to draw from during the milking period.

Published: 23.02.11
Updated: 25.02.11
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