PROTEIN SUPPLEMENTATION AND 48-HOUR CALF REMOVAL EFFECTS ON RANGE COWS

In 1984, 99 Angus X Hereford cows (4- to 6-yr-olds) were assigned rand omly to a 4-yr, 2 X 2 factorial study. Treatment assignment was perman ent, and no new cows were added during the study. By 1987, 71 cows rem ained, and over-all, 335 complete cow-calf data sets were used. Main e ffect treatments were beginning time (prepartum [PRE] vs postpartum [P OST]) for crude protein (CP) supplementation (twice weekly feeding of 41% CP cottonseed meal pellets at 1.58 kg . cow-1 . feeding-1) and tem porary calf removal (48 hour [48-H] vs 0 hour [CONT])just before the b reeding season. For analyses, sex of calf was included as a third main effect (2 X 2 X 2) and year was included as a random factor; the 4-wa y interaction served as the testing term for repeated measures over ye ars. Year was the dominant source of variation for most traits; we att ributed this mainly to different amounts and timing of precipitation a mong years. Very few interactions were observed. The PRE supplemented cows had reduced (P < 0.01) spring body weight losses and higher prebr eeding body condition scores (4.9 vs 4.5; P < 0.01) compared with POST cows. Reproductive performance did not differ between PRE and POST co ws. Use of 48-H calf removal vs CONT did not influence (P > 0.10) repr oductive traits measured. Likewise, 48-H treatment did not impair heal th or reduce weaning weights of calves. In a separate, within-year ana lysis used to examine age of dam effects, productivity of 4-yr-old cow s during 1984 was slightly below that of older cows for some traits. C ow age effects were not detected in other years. We conclude that cont rol cows in our study were approaching optimum fertility and productio n levels in concert with their environment and that improvement beyond these levels with the treatments imposed was unlikely.