Browsing by Author "Wallace, Joe D."

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Influence of Ruminally Dispensed Monensin and Forage Maturity on Intake and Digestion.
(1993-05) Fredrickson, Eddie L; Galyean, M. L.; Branine, M. E.; Sowell, Bok F.; Wallace, Joe D.
Eight ruminally cannulated crossbred steers (average weight 336 kg) grazing native blue grama (Bouteloua gracilis [H.B.K.]) rangeland were used in a repeated measures design to evaluate effects of monensin ruminal delivery devices (MRDD) and forage phenology on ruminal digestion. Three periods were assessed: mid-August (Aug.), early October (Oct.), and mid-November (Nov.). One MRDD was placed in the reticulum of 4 steers via the ruminal cannula 21 days before each period. Intake was estimated using total fecal collections. Diet samples were collected using 3 esophageally fistualted steers. Ruminal fill was measured by ruminal exacuation; rate and extent of in situ ruminal neutral detergent fiber disappearance were estimated before ruminal evacuations. Ruminal passage rates, retention time, and apparent total tract organic matter digestibility were estimated using indigestible neutral detergent fiber. In vitro organic matter disappearance of esophageal masticate did not differ (P>.05) in Aug. and Oct. (average of 53.7%), but declined (P<.05) in Nov. (48.7%), whereas organic matter digestibility was greater (P<.10) in Aug. (62.3%) than in either Oct. (55.2%) or Nov. (53.9%). Release of monensin from the bolus (68 mg day-1) was less than expected (100 mg day-1). Intake, organic matter digestibility, ruminal passage rates, retention time, pH, and ammonia were not affected (P>.10) by MRDD. In situ neutral detergent fiber disappearance at 96 hours was decreased (P<.10) by MRDD (68 vs 65% for control and MRDD, respectively). As the grazing season progressed, intake declined (P<.10), whereas ruminal fill and retention time increased (P<.05), and passage rate of indigestible neutral detergent fiber decreased (P<.05). At 48 hours in situ neutral detergent fiber was greatest (P<.05) in Aug. and least (P<.05) in Nov.
Protein Supplementation and 48-Hour Calf Removal Effects on Range Cows
(1992-03) Sowell, Bok F.; Wallace, Joe D.; Parker, Eugene E.; Southward, Morris G.
In 1984, 99 Angus × Hereford cows (4- to 6-yr-olds) were assigned randomly to a 4-yr, 2 × 2 factorial study. Treatment assignment was permanent, and no new cows were added during the study. By 1987, 71 cows remained, and over-all, 335 complete cow-calf data sets were used. Main effect treatments were beginning time (prepartum [PRE] vs postpartum [POST]) for crude protein (CP) supplementation (twice weekly feeding of 41% CP cottonseed meal pellets at 1.58 kg • $\text{cow}^{-1}$ • $\text{feeding}^{-1}$) and temporary calf removal (48 hour [48-H] vs 0 hour [CONT]) just before the breeding season. For analyses, sex of calf was included as a third main effect (2×2×2) and year was included as a random factor; the 4-way interaction served as the testing term for repeated measures over years. Year was the dominant source of variation for most traits; we attributed this mainly to different amounts and timing of precipitation among years. Very few interactions were observed. The PRE supplemented cows had reduced (P<0.01) spring body weight losses and higher prebreeding body condition scores (4.9 vs 4.5; P<0.01) compared with POST cows. Reproductive performance did not differ between PRE and POST cows. Use of 48-H calf removal vs CONT did not influence (P>0.10) reproductive traits measured. Likewise, 48-H treatment did not impair health or reduce weaning weights of calves. In a separate, within-year analysis used to examine age of dam effects, productivity of 4-yr-old cows during 1984 was slightly below that of older cows for some traits. Cow age effects were not detected in other years. We conclude that control cows in our study were approaching optimum fertility and production levels in concert with their environment and that improvement beyond these levels with the treatments imposed was unlikely.