Biomedical subjects

W E Wyatt

Publications and source records attributed to W E Wyatt.

15 recordsLinked to original sources

PubMed1997

Performance of Angus and Brangus cow-calf pairs grazing Alicia bermudagrass and common bermudagrass-dallisgrass pastures.

This research was designed to examine genotype x environment interactions in cow-calf growth performance of grazing animals. Angus and Brangus cow-calf pairs (minimum of six per breed) were allowed to rotationally graze (14-d intervals) treatment pastures from approximately May through early October in each of 2 yr. Treatment pastures contained relatively pure stands of Alicia bermudagrass (AP) or a mixed stand of common bermudagrass and dallisgrass (CDP). Forage allowance was equalized, using "put-and-take" cow-calf pairs, among forage and breed types at the initiation of each 14-d grazing interval. Forage samples were obtained in each paddock at the initiation of each grazing interval. Forage CP concentration was greater (P < .05; 13.5 vs 11.6%) and NDF concentration was less (P < .05; 63.8 vs 70.6%) for CDP than for AP. Daily weight loss was similar for Angus and Brangus cows, but it was greater (P < .05) for cows grazing AP than for cows grazing CDP. Calf ADG during the grazing season was 35% greater (P < .05) for CDP than for AP pastures and was 23% greater (P < .01) for Brangus than for Angus calves. Relative performance of Angus and Brangus cow-calf pairs was consistent between forages; no breed x forage interactions were observed.

Animal Feed↗

PubMed1995

Monensin and ammoniation or urea supplementation of bermudagrass hay diets for steers.

One growth trial using crossbred beef steers (297 +/- 2 kg, Exp. 1) and one metabolism trial using Holstein steers (405 +/- 14 kg, Exp. 2) were conducted to evaluate effects of ammoniation (3% of hay DM, added as anhydrous NH3) vs urea supplementation with or without monensin supplementation of mature 'Alicia' bermudagrass hay-based diets for steers. Ammoniation (P < .05), but not urea (P = .26) or monensin (P = .70) supplementation, increased ADG in Exp. 1. In Exp. 2 ammoniation increased hay DMI (P < .05), but urea (P = .88) or monensin (P = .16) had no effect. Supplementation with either monensin (P < .05) or urea (P < .05) decreased ruminal total VFA concentrations. Monensin also decreased the ruminal acetate:propionate ratio (P < .001) and increased ruminal pH (P < .05). Addition of urea to the concentrate supplement decreased the rate of concentrate intake. Both the rate (P < .05) and the potential extent (P < .001) of ruminal forage in situ DM and NDF disappearance were increased by ammonia treatment. Dietary interactions (P < .10) were detected between monensin and ammoniation for rate and potential extent of in situ NDF disappearance and between monensin and urea supplementation (P < .05) for ruminal total free amino acid concentrations. Decreased concentrations of VFA and lower forage digestibilities observed with monensin supplementation in Exp. 2 may explain the failure of monensin to affect ADG in Exp. 1.

Ammonia↗

PubMed1994

Prepartum body condition and weight influences on reproductive performance of first-calf beef cows.

Data were collected on 476 spring-calving, primiparous cows at six locations in Louisiana over a 2-yr period. Objectives of the study were to evaluate changes in prepartum body condition score (BCS) and BW of heifers when fed varying energy levels and to determine the influences of prepartum BCS and BW changes and BCS at calving on postpartum traits. Heifers were allocated to one of three energy levels from approximately 90 d prepartum to parturition. The diets were formulated to provide low, recommended, and high energy levels based on TDN requirements. After calving, cows were placed on annual ryegrass pasture and managed similarly at each location. Weight and BCS at calving were greater (P < .05) for females with higher BCS at 90 d prepartum (IBCS) and for those assigned to higher energy levels. Calving and calf growth traits were not affected (P > .05) by IBCS, energy level, prepartum changes in BCS and BW, or BCS at calving. Prepartum changes in BCS and BW regulated by varying energy levels had no effect (P > .05) on postpartum reproduction; however, BCS at calving influenced (P < .03) pregnancy rate and days to pregnancy. Cows with BCS 6 and 7 at calving had higher (P < .05) pregnancy rates (87.0 and 90.7%) than those with BCS 4 and 5 (64.9 and 71.4%). Interval to pregnancy for cows with BCS 4 at calving was 10 to 18 d longer (P < .05) than for those with BCS > or = 5.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1991

Effect of supplemental lysocellin and tetronasin on growth, ruminal and blood metabolites, and ruminal proteolytic activity in steers grazing ryegrass.

Forty-eight Angus and Brangus steers (249 kg initial BW) were used in a randomized complete block design. Steers grazed annual ryegrass (Lolium multiflorum [L.] Lam.) for 107 d and were sampled at 35 and 70 d. Treatments consisted of a corn supplement (C) or corn supplement plus either 80 mg.steer-1.d-1 of lysocellin (L) or 60 mg.steer-1.d-1 of tetronasin (T). When compared with C, ADG of L- and T-fed steers was higher (P less than .05) for the complete 107-d study (1.15 vs 1.25 kg/d). At 35 d, ruminal acetate:propionate ratio tended (P = .07) to be higher for C than for L- and T-fed steers (4.6 vs 3.8). When compared with T, steers fed L tended (P = .11) to have higher acetate:propionate ratios. Ruminal concentrations of ammonia and free amino acids were not affected (P greater than .05) by treatment, but ruminal proteolytic activity tended (P = .13) to be lower for L- and T-fed than for C steers at 70 d. Ionophores did not alter (P greater than .05) ruminal mineral concentrations, but ruminal Mg concentration tended (P = .14) to be higher for T- than for L-fed steers at 70 d. When compared with L- and T-fed steers, C steers had lower (P less than .05) plasma concentrations of Mg (23.7 vs 21.9 mg/liter) and Ca (113.0 vs 104.2 mg/liter) at 35 d. Plasma mineral concentrations were similar (P greater than .05) for L- and T-fed steers. Data are interpreted to indicate that L and T may improve ADG, decrease ruminal acetate:propionate ratio, and alter mineral metabolism.

Amino Acids↗

PubMed1990

Effects of breed and wintering diet on heifer postweaning growth and development.

Fifteen spring-born Angus (AN) and 25 Brangus (BN) weanling heifers were used in a 2x5 factorial arrangement of treatments to evaluate the effects of breed and postweaning winter diet on heifer growth and development. Dietary treatments were warm-season perennial grass hay (H), ammoniated H (AH), H plus .68 kg/d cottonseed meal (HP), H plus .45 kg/d cottonseed meal plus 1.37 kg/d ground corn (HPE) and HPE plus 200 mg/d monensin (HPEM). Mean initial weight and age for the 107-d feed trial were 207 kg and 270 d. Brangus had .06 kg greater (P less than .05) ADG than AN during the trial. Although digestible DM intake (DDMI) relative to body weight was greater (P less than .10) for AN than for BN, ADG:DDMI was greater (P less than .05) for BN than for AN. Heifers fed H and AH lost weight, but heifers fed AH had 50% (P less than .05) less daily weight loss than those fed H. Daily gain increased (P less than .05) incrementally in response to sequential supplement additions of cottonseed meal (AH vs HP; -.10 vs .17 kg), ground corn (HP vs HPE; .17 vs .29 kg) and monensin (HPE vs HPEM; .29 vs .39 kg). Hay DM intake relative to body weight and DDMI were increased (P less than .01) by ammoniation. Intake did not differ between HPE and HPEM. Diet affected age at puberty (P less than .05), which decreased with increased dietary components. Weight differences among diet groups following the winter feed trial were largely eliminated prior to breeding. Nevertheless, H- and AH-fed heifers collectively weighed less (P less than .01) prior to breeding than did heifers of supplemented diet groups. Reproductive development tended to be adversely affected by weight loss during the postweaning period.

Age Factors↗

PubMed1989

Effects of breed and wintering diet on growth, puberty and plasma concentrations of growth hormone and insulin-like growth factor 1 in heifers.

Twenty-five Brangus (BR) and 15 Angus (AN) heifers were used to study the effects of breed and wintering diet on average daily gain (ADG), onset of puberty and plasma concentrations of growth hormone (GH) and insulin-like growth factor 1 (IGF-1). Wintering diets (fed for 107 days beginning November 15) consisted of the following: 1) native grass hay (NGH), 2) ammoniated NGH, 3) NGH plus cottonseed meal, 4) Diet 3 plus corn and 5) Diet 4 plus monensin. After wintering, heifers were transferred to ryegrass pasture for 70 days. Mean ADG during the wintering phase were -.20, -.10, .17, .29 and .39 kg for heifers fed Diets 1 through 5, respectively (P less than .01). ADG was greater (P less than .05) for BR than for AN heifers. Plasma concentrations of GH were higher (P less than .05) in heifers fed Diets 1 and 2 than in heifers fed Diets 3, 4 or 5. Plasma concentrations of IGF-1 were lowest in heifers fed Diet 1 and highest in heifers fed Diets 4 and 5. During ryegrass grazing, GH concentrations were similar for all groups. However, concentrations of IGF-1 were higher (P less than .05) in heifers fed Diets 3, 4 and 5 than in heifers fed Diets 1 and 2. Age at puberty (onset of cyclic progesterone concentrations) was greatest in heifers fed Diet 1 and lowest in heifers fed Diet 5. Weight at puberty was not affected (P greater than .10) by wintering diet but was greater (P less than .01) in BR than in AN heifers. Therefore, negative ADG appears to be associated with elevated plasma GH concentrations in heifers, and plasma IGF-1 concentration appears to be a more accurate indication of nutritional status than plasma concentrations of GH.

Aging↗

PubMed1989

Dose-response relationship of tetronasin administered to grazing steers.

Two grazing experiments were conducted to evaluate the dose-response relationship of steers to the ionophore tetronasin. Bermudagrass-based pastures were grazed 126 d in Exp. 1, and annual ryegrass or an annual ryegrass-berseem clover mixture was grazed 112 d in Exp. 2. Tetronasin was administered in ground corn (.91 kg/hd) fed daily to provide dosages of 0, 7.5, 15, 30, 60 or 90 mg. One hundred forty-four steers (220 kg, Exp. 1; 196 kg, Exp. 2) were allocated to treatment groups of six steers within four initial weight blocks in Exp. 1 and within two initial weight blocks, assigned to two forage types in Exp. 2. Initial weight blocks were confounded with four pasture blocks, divided in six 1.35-ha paddocks. Treatment groups were rotated among paddocks within pasture block every 2 wk. Stepwise tetronasin addition resulted in a linear increase (P less than .05) in the proportion of propionic acid and a linear decrease (P less than .05) in the proportion of acetic acid and the acetic to propionic acid ratio in both experiments. Total VFA concentrations were not altered in Exp. 1 but they decreased linearly in Exp. 2 with tetronasin addition. Maximal observed improvement in daily gain (.1 kg) occurred at a dosage of 30 mg.hd-1.d-1 in Exp. 1 and 90 mg.hd-1.d-1 in Exp. 2. Daily gain increased linearly (P less than .06) with tetronasin level in both experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Preventing adverse effects on the temporomandibular joint through orthodontic treatment.

The temporomandibular joint is one of the most complicated working assemblies in the human body. We are just now beginning to understand it and give it the respect and careful treatment it deserves as an integral functioning part of the dental anatomy. No orthodontic procedure can be performed in isolation without considering its possible effect on the temporomandibular joint. Therefore, the following recommendations are made for diagnosis and treatment planning. Etiologic factors that might cause upward and backward pressures on the mandible should be reduced as much as possible. Mechanotherapy that may cause upward and backward pressures on the condyles is not recommended. Final detailed correction of dental abnormalities should always consider optimal temporomandibular health and function. Retention procedures should be planned to provide a proper path of closure to minimize or prevent possible retrogressive posttreatment changes. It is the author's hope that the hypotheses and suggestions in on TMJ problems and on the preventive role of orthodontics in the patient's treatment.

Extraoral Traction Appliances↗

PubMed1974