Dairy cows

Various sources of lipid have been incorporated into ruminant diets to increase the energy density and provide the large amount of energy needed for slaughter animals to achieve market weight or for dairy cows to produce milk (see Milk and milkproducts). Fats also reduce the dustiness of feeds, increase the feedstuffs abiUty to pellet, and improve feed acceptabiUty. 

In 1990, U.S. milk production was 67.4 X 10 t from neatly 10.1 X 10 cows. In the United States there has been an increase in quantity of production with a decrease in number of dairy cows. The wodd production in 1987 was 463.4 X 10 t from 50 X 10 cows. Table 12 gives the 1990 production and utilization of fluid and milk products (15). Table 13 gives the total U.S. pet capita consumption. 

The same principle has been appHed to other mammals, particularly ewes and goats, as well as dairy cows (Table 22 Table 22. Use of Milk-Producing Animals for Biotechnology... 

The ingestion pathway is much more complicated than the others since the radionuclides, except those in drinking water, have to be taken up by the plants and then consumed by humans in either vegetable or animal form. Of the various pathways, the milk pathway is particularly important because a dairy cow consumes a large amount of vegetation and concentrates radionuclides (e.g,... 

Metges, C, Kempe K. and Schmidt, H.-L. 1990 Dependence of the carbon-isotope contents of breath carbon dioxide, milk, serum and rumen fermentation products on the 8 Cvalue of food in dairy cows. British Journal ofNutritim 63 187-196. 

Because dairy cows or calves are culled for meat production, four different methods to allocate the enviromnental emissions at the farm and outside the boimdary of the fluid milk supply chain may be used (Cederberg and Stadig, 2003). The allocation method assumes, (1) no allocation is used and only milk production impacts the enviromnent ... 

The milk production stage is the largest source of GHG emissions over the entire life cycle of fluid milk production. CH4 is generafed primarily through enteric fermentation of dairy cows and also through the microbial, anaerobic decomposition of manure. Manure deposifed on soil or handled as a solid, an aerobic process, emits little CH4. However, manure generates CH4 when stored under the aerobic conditions of a lagoon. 

Boadi, D., Benchaar, C., Chiquette, J., and Masse, D. (2004). Mitigation strategies to reduce enteric methane emissions from dairy cows Update review. Can. J. Anim. Sci. 84,319-335. 

Holtshausen, L., Chaves, A. V., Beauchemin, K. A., McGinn, S. M., McAllister, T. A., Odongo, N. E., Cheeke, P. R., and Benchaar, C. (2009). Feeding saponin-containing Yucca schidigera and Quillaja saponaria to decrease enteric methane production in dairy cows. /. Dairy Sci. 92, 2809-2821. 

Kinsman, R., Sauer, F. D., Jackson, H. A., and Wolynetz, M. S. (1995). Methane and carbon dioxide emissions from dairy cows in full lactation monitored over a six-month period. 

Similar findings on dairy farms in Canada were reported by Stonehouse, et al. (2001). The superior economic performance on organic dairy farms was attributed to lower costs of production for almost all material inputs, including dairy herd replacements and livestock feeds. The organic dairy farmers used more land for feed crop production for the dairy cows in order to be as self-sufficient as possible. The conventional dairy farmers imported crop seeds, synthetic chemical fertilisers and pesticides, feedstuffs and herd replacements, with more of their land being devoted to cash crops. 

Finally, there is the question of the accuracy of the prediction. It is highly likely that any increase in accuracy will also increase the cost. For a start, the smallest animal likely to be used in grazing is a sheep, which will consume 0.5 t of dry matter per annum. This means that there is little point in trying to predict within less than 0.5 t of dry matter. With an all-dairy farm, accuracy can be less precise, because a dairy cow is likely to eat 4.2 t of dry matter per head per annum. 

Figures for the numbers of organic dairy cows in Europe (Foster Lampkin, 1999) indicated that in 1996 Great Britain still had only 3436 organic dairy cows, compared to Austria (87 068), Switzerland (32 504) and Denmark (21417). By 1999 Padel, et al. (2000) calculated that there were 45 million litres of organic milk produced in the UK. From 2000 to 2003 organic milk production in the UK increased by approximately 600%, and the total organic milk collected in 2003 was 293.4 million litres, of which 62% was sold as organic (Soil Association, 2003).

The organic farmer must be fully satisfied that close grazing does not result in under-nutrition. It need not, but any system based on utilising herbage as fully as possible tends to make the dairy cows eat second or third choice herbage, which may reduce intake slightly and thus milk yield. 

Rotational grazing This requires either electric fencing plus a back fence, which is comparatively easy with dairy cows, or the creation of... 

This is of great importance for dairy cows, as the indoor period may well last for more than half the year, and organic silage is almost impossible to purchase. It is still impossible to forecast weather conditions much... 

July to housing. For a dairy farm with half site class 2 fields and half site class 3 fields, yielding 12 t dry matter per ha per annum and utilising this with an efficiency of 67%, annual stocking rate would be 1.9 dairy cows per ha. With a spring to autumn stocking rate ratio of 1.5 1, stocking rate from turnout to mid-July would be 2.28 cows per ha and from mid-July to October would be 1.52 cows per ha. 

In a comparison of reproductive performance between organic and conventional dairy herds in Norway, Reksen, et al. (1999) found that organic dairy cows bred less successfully when mated in winter than... 

Rex Paterson Memorial Study, British Grassland Society, December 1982. Webster, J. (1993) Understanding the Dairy Cow, 2nd edn. Blackwell Science, Oxford. 

Barley is an important crop, with the best quality grains sold for malting and the remainder used for feeding all classes of stock, especially pigs, dairy cows and intensively fed beef. Barley straw can be used for bedding and as a maintenance ration. Barley is a shallow-rooted crop which grows well on chalk and limestone soils, with a preferred pH of 6.5. Its place in the rotation can be when soil fertility is low, which means that it can follow a previous cereal crop such as wheat. 

Increased fat content in milk The sow has responded to increased fibre in the diet, like the dairy cow, by increasing the production of acetate, which has then beneficially increased the fat content of the milk. 

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