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  • Author or Editor: Gary P. Rupp x
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Summary

Six steer calves, surgically fitted with a permanent cannula in the rumen, omasoabomasal orifice, abomasum, and duodenum were used to determine total digesta flow and volatile fatty acid (vfa) concentration at various points in the digestive tract. The omasoabomasal cannula had a flexible nylon sleeve that could be exteriorized through the abomasal cannula to collect omasal effluent.

Three experiments were conducted: 95% concentrate fed at maintenance (2,670 g of organic matter intake/d); 95% concentrate fed ad libitum (3,484 g of organic matter intake/d); and brome hay fed ad libitum (2,927 g of organic matter intake/d). Calves were offered the diet in 12 portions daily. Each experiment included a 14-day adaptation period and a 2-day sample collection period during which chromic oxide was used as a digesta flow marker. In all 3 experiments, vfa concentration was greatest in the rumen sample (84 to 109 mM), intermediate in the omasal sample (32 to 40 mM), and lowest in the duodenal sample (7 to 14 mM, P < 0.01). Total fluid flow at the duodenum was 13 to 18 L/d greater than flow at the omasum (P < 0.10). Omasal vfa flow was twofold greater than duodenal vfa flow (P < 0.05). There was a net fluid increase and net disappearance of vfa across the abomasum. The cannulation technique was useful for repeated collection of omasal effluent for at least 3 months.

Free access
in American Journal of Veterinary Research

Objective

To evaluate the breeding soundness examination procedure in plains bison bulls.

Design

Multiyear (1993 through 1997) cross-sectional clinical procedure evaluation.

Animals

Two hundred thirty-four 28- to 30-month-old bison bulls at Custer State Park

Procedure

Breeding soundness examinations were performed on all bison bulls using 1992 Society for Theriogenology guidelines for beef cattle semen evaluation and reproductive tract examination. Linear and logistic regression analyses were used to detect correlations and associations among breeding soundness examination variables.

Results

Scrotal circumference (SC) was significantly correlated with body weight, percentage of normal spermatozoa, percentage of primary spermatozoal defects, and percentage of motile spermatozoa. Scrotal circumference was positively associated with increased odds of semen collection, satisfactory motility (≥ 30% motility), satisfactory morphology (≥ 70% normal spermatozoa), and simultaneous satisfactory motility and morphology. Receiver-operator characteristic curve analysis selected 29 cm as the optimal SC cutoff most predictive of simultaneous satisfactory spermatozoal motility and morphology. Only 36.2% (83/229) of the bison bulls had a SC of 29 cm or greater and satisfactory spermatozoal motility and morphology.

Clinical Implications

SC is a good indicator of adequate spermatozoal motility and structure in bison. We recommend use of 30% spermatozoal motility, 70% normal spermatozoal morphology, and 29-cm SC as minimal satisfactory measurements for breeding soundness examinations of 28- to 30-month-old bison bulls that have been raised on forage-based nutrition. (J Am Vet Mec Assoc 1999;214:1212–1217)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare methods for identification of bulls that were carriers for Tritrichomonas foetus during an outbreak on a large beef ranch and determine whether the percentage of nonpregnant cows was associated with the percentage of bulls infected with T foetus.

Design—Epidemiological study.

Animals—121 Angus and Hereford bulls (1.5 to 6 years old) and 2,960 Angus-cross cows (2.5 to 14 years old) managed as 5 herds on a Nebraska beef ranch.

Procedures—3 sequential preputial scrapings collected from the bulls at 12- to 27-day intervals were cultured, and cultures were examined for live T foetus daily for 5 days. On day 5, aliquots of the culture fluid were tested by means of T foetus-specific gel and real-time PCR assays. Cows were tested for pregnancy by means of rectal palpation.

Results—For 361 preputial scrapings obtained from 121 bulls, results of culture and gel PCR assay were in close agreement. The real-time PCR assay had similar sensitivity to culture and the gel PCR assay but generated more false-positive results. Twenty-four of the 121 (19.8%) bulls were identified as infected with T foetus. For the 5 ranch herds, there was a positive linear correlation between percentage of infected bulls (range, 0% to 40%) and percentage of nonpregnant cows (range, 8.3% to 19.2%).

Conclusions and Clinical Relevance—Results suggested that a combination of culture and the gel PCR assay performed on 3 sequential preputial scrapings was the best method for identifying bulls that were carriers for T foetus during this herd outbreak.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate associations between neonatal serum IgG1 concentration and pre- and postweaning morbidity and mortality rates and average daily gains (ADGs) in beef calves and define a cutoff point for serum IgG1 concentration necessary for optimal health and performance of beef calves.

Design—Nonconcurrent cohort study.

Animals—1,568 crossbred beef calves.

Procedure—Single radial immunodiffusion was used to quantitate IgG1 concentration in sera collected from calves between 24 and 72 hours after birth. Logistic regression, ANCOVA, and likelihood ratios were used to analyze data.

Results—In the preweaning period, lower perinatal IgG1 concentrations were significantly associated with higher morbidity rates, higher mortality rates, and lower ADGs. Calves with serum IgG1 concentration < 2,400 mg/dL were 1.6 times as likely to become ill before weaning and 2.7 times as likely to die before weaning as calves with higher serum IgG1 concentrations. Calves with serum IgG1 concentration of at least 2,700 mg/dL weighed an estimated 3.35 kg (7.38 lb) more at 205 days of age than calves with lower serum IgG1 concentration. No significant association of serum IgG1 concentration with feedlot morbidity, death, or ADG was identified.

Conclusions and Clinical Relevance—By use of likelihood ratios, the threshold of serum IgG1 concentration for optimal health and performance of calves was higher than values reported previously. Implementation and maintenance of management and intervention strategies designed for early detection and treatment of calves at risk for failure of passive transfer will likely result in increases in preweaning health and performance parameters.

Full access
in Journal of the American Veterinary Medical Association