Effects of feeding low and high levels of energy on milk production of dairy cattle under Philippine conditions

The experiment consisted of two trials. In each trials, nine lactating cows (Holstein x Red Sindhi) were used in completely randomized design, to study the effects of varying dietary energy on body weight maintenance, milk production, milk composition, feed efficiency, physiological responses and income over fed costs. Feeding period was divided into standardization (two weeks), preliminary (two weeks), and comparison (twelve weeks) periods. Three different rations were given to the three respective groups of cows, supplying 20 percent below the USNRC energy requirements (Ration A); 110 percent NRC energy requirements (Ration B); and 30 percent above the NRC energy requirements (Ration C). Digestible protein intakes were found at 106 percent, 112 percent, and 112 percent of NRC standard, for treatments A, B, and C, respectively. Changes in body weight expressed as percentage of initial body weight were 6.47 percent, -3.58 percent and -0.92 percent for cows on rations A, B, and C, respectively. The differences between C and A, and C and B were significantly at 0.01 and 0.05 probability levels, respectively. Adjusted daily 4 percent fat corrected milk (FCM) production of the cows on rations A, B, and C, was 4.58, 5.10 and 6.90 kg, respectively. This was found to be significantly (P0.01) greater in favor of cows on ration C than those on other treatments. Daily mean gross efficiency of cows fed with Rations A, B, and C was 0.83, 1.01 and 1.08, respectively. No statistical significance were found. Adjusted daily mean fat production of cows fed with rations A, B, and C was 183.47 g, 199.14 g and 267.16 g, respectively. The mean was significantly higher (P0.01) in favor of C over A and B. The differences in terms of milkfat content, and total solids were not significant. However, the means for protein content of the cows on ration C were found to be significantly higher than the values obtained on rations A (P0.01), and B (P0.05). Solids-non-fat content obtained on ration C was significantly (P0.05) higher than the means on the other two rations. No significant differences were found in body temperature and pulse rate; however, animals on rations B and C had higher (P0.01) respiratory rate than those on ration A. Income over feed costs obtained from treatment A, B, and C for a twelve-week period was P399.51, 517.47, and 678.54, respectively. The mean was significantly greater in favor of C over A (P0.01) and B (P0.05). In general, under conditions of this study, it would appear that the energy requirements of the stall-fed lactating cows are far above the USNRC standard.