Phosphorus and Calcium Utilization and Requirements in Farm Animals
Ever since animal agriculture began there has been a drive to improve the productivity of our livestock for economic and survival reasons. For that reason research into animal production has been concerned largely with this objective. The limits on production in early days of agriculture were...
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| Những tác giả chính: | , |
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| Định dạng: | Sách |
| Ngôn ngữ: | English |
| Được phát hành: |
CABI
2014
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| Những chủ đề: | |
| Truy cập trực tuyến: | https://scholar.dlu.edu.vn/thuvienso/handle/DLU123456789/36880 |
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| Thư viện lưu trữ: | Thư viện Trường Đại học Đà Lạt |
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| Tóm tắt: | Ever since animal agriculture began there has been a drive to improve the
productivity of our livestock for economic and survival reasons. For that reason
research into animal production has been concerned largely with this objective.
The limits on production in early days of agriculture were determined by the
natural regenerative processes of the soil and the cycling of crop and animal
wastes in a closed, ecologically sustainable system (Conway and Pretty, 1991).
Since the Second World War, a tremendous improvement in agricultural production has been observed. This is mainly due to national and international policies
that were favourable to farming such as the European Common Agricultural
Policy and major technological advances in inputs and techniques available to
farmers.
Intensification of animal production led to a serious imbalance between
inputs of nutrients in purchased fertilizers, concentrates and forages, and the respective outputs in milk and meat and nutrient accumulation in the environment.
Several surveys (e.g. Sansinena et al., 1999; Satter and Wu, 1999; Sink et al., 2000;
Kebreab et al., 2008) have revealed that dairy producers in the United States
and Canada routinely include 0.45 to 0.50% dietary P in feed. This is in excess
of recommendations by NRC (2001) and in excess of the needs of lactating cows
(Wu et al., 2001; Valk et al., 2002). Castillo et al. (2009) reported that 62.5% of
California dairies fed P in the amounts 120–200% of NRC requirements to their
herd. Similarly, 21 out of 40 commercial dairy farms tested in Merced County,
California, had 120–200% of NRC requirements of Ca. None of the farms fed P
below requirement and all farms fed iron and manganese over 200% of NRC
requirements. |
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