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The Effects of Feeding Low and High Levels of Energy on Milk Production of Dairy Cattle under Philippine Conditions
Thesis Abstract:
Experiments were conducted on lactating cows (Holstein x Red Sindhi) to determine the effects of varying dietary energy level on body weight maintenance milk production, milk composition, feed efficiency, physiological responses and income-over-feed costs.
Feeding periods were divided into standardization (2 weeks), preliminary (2 weeks), and comparison (12 weeks). Three different rations were given to the three respective groups of cows: Ration A supplying 20% below the USNRC energy requirements; ration B, 110% NRC energy requirements; and ration C, 30% above the NRC energy requirements. Digestible protein intakes for treatments A, B, and C were found at 106, 112 and 112% of NRC standard, respectively.
Results showed that a majority of the experimental cows lost weight. Changes in body weight expressed as percentage of initial weight were -6.47, -3.58 and -0.92% for cows on rations A, B and C, respectively. The differences between C and A and between C and B were statistically significant.
Adjusted daily 4% FCM productions of the cows on rations A, B and C were 4.58, 5.10 and 6.90 kg, respectively. Production of cows on ration C was significantly higher than those on other treatments.
Differences in mean gross efficiency of cows fed the three rations were not statistically significant.
Adjusted daily mean fat productions of cows on rations A, B and C were 183.47, 199.14 and 267.16 g, respectively. Fat production of cows fed ration C was significantly higher than those on rations A and B.
Differences in milkfat content and total solids were not significant. However, protein and solids-non-fat contents of milk produced by cows on ration C were significantly higher than those on rations A and B.
Body temperature and pulse rate of the animals did not differ significantly. However cows on rations B and C had higher respiratory rate than those on ration A.
Income-over-feed costs obtained from treatments A, B and C for a 12-week period were around 399, 517 and 678 pesos, respectively. The mean for C was significantly greater than those for A and B.
In general, under conditions of this study, the energy requirements of stall-fed lactating cows seemed far above the USNRC standard.
