Fred M. Hopkins

Breeding soundness evaluations of 3648 yearling beef bulls using the 1993 Society for Theriogenology guidelines

Our objective was to perform a retrospective analysis of breeding soundness evaluations (BSEs) as classified by the 1993 Society for Theriogenology (SFT) guidelines [Chenoweth et al., Guidelines for using the bull breeding soundness evaluation form, in: Theriogenology Handbook, 1993, pp. B-10]. Data included BSE information obtained from five performance-testing stations in South Carolina (SC1, SC2, SC3) and Tennessee (TN1, TN2) from 1986 through 1999 on 3648 Angus, Brangus, Charolais, Chianina, Gelbvieh, Limousin, Polled Hereford, Santa Gertrudis, Simbrah, and Simmental bulls. Analyses were simplified by classifying all bulls as either satisfactory or unsatisfactory potential breeders. Of the 3648 bulls evaluated, 76.2% were classified as satisfactory potential breeders. Of all bulls evaluated, 4.0% were unsatisfactory due to inadequate spermatozoal motility, 7.0% due to inadequate spermatozoal morphology and 2.6% due to a combination of inadequate motility and morphology. Unsatisfactory classifications due to non-spermatozoal parameters out of all bulls were 10.2%, with 7.1% for inadequate scrotal circumference and 3.1% for physical abnormalities. For satisfactory and unsatisfactory bulls, respectively, means and standard deviations were 35.8 +/- 2.7 and 33.0 +/- 4.1 cm (P < 0.001) for scrotal circumference, 63 +/- 18 and 35 +/- 24% (P < 0.001) for percent motility, and 86 +/- 7 and 63 +/- 21% (P < 0.001) for percent normal morphology.

The New Society for Theriogenology Breeding Soundness Evaluation System

In 1993, The Society for Theriogenology published revised standards for breeding soundness evaluation of bulls. These revised standards replaced the old semen score format with minimum acceptable scores for scrotal circumference (varies with age), motility (30% or fair), and morphology (70%).

Fertility aspects in yearling beef bulls grazing endophyte-infected tall fescue pastures

During a 2-year study, yearling beef bulls were used to determine the effects of grazing on endophyte-infected tall fescue on endocrine profiles, semen quality and fertilisation potential. Bulls were allotted to graze tall fescue pastures infected with Neotyphodium coenophialum (E+; n = 20 per year) or Jesup/MaxQ (Pennington Seed, Atlanta, GA, USA; NTE; n = 10 per year). Bulls were grouped by scrotal circumference (SC), bodyweight (BW), breed composites and age to graze tall fescue pastures from mid-November until the end of June (within each year). Blood samples, BW, SC and rectal temperatures (RT) were collected every 14 days. Semen was collected from bulls every 60 days by electroejaculation and evaluated for motility and morphology. The developmental competence of oocytes fertilised in vitro with semen from respective treatments was determined. Bulls grazing E+ pastures had decreased BW gain (P < 0.01), increased overall RT (P < 0.01) and decreased prolactin (P < 0.01) compared with animals grazing NTE pastures. Neither percentage of normal sperm morphology nor motility differed between bulls grazed on the two pasture types. Semen from E+ bulls demonstrated decreased cleavage rates (P = 0.02) compared with semen from NTE bulls. However, development of cleaved embryos to the eight-cell and blastocyst stages did not differ between the two groups. In conclusion, semen from bulls grazing E+ tall fescue resulted in decreased cleavage rates in vitro, which may lower reproductive performance owing to reduced fertilisation ability.

Outcomes of breeding soundness evaluation of 2898 yearling bulls subjected to different classification systems.

This study is a retrospective analysis comparing data on yearling bull breeding soundness evaluation (BSE) subjected to 3 different classification systems: the Society for Theriogenology (SFT) 1983 and 1993 systems, and the Western Canadian Association of Bovine Practitioners (WC) 1993 system. Data were collected at 5 performance bull-test stations located in South Carolina and Tennessee from 1986 through 1996. Yearling bulls (n=2898) that were 10 to 20 mo of age were used in the analysis. To simplify analysis, bulls were determined to be either satisfactory or unsatisfactory potential breeders (including those classified as questionable, deferred or unsatisfactory). Data were analyzed 1) within location where a location was treated as an individual experiment, 2) with breeds and locations collapsed, and 3) within age-group where each age-group was treated as an individual experiment. An ANOVA was performed using GLM procedures of SAS, and this model was used to generate least square means for the proportion of bulls classified as satisfactory and the 5 possible unsatisfactory outcomes due to inadequacies in scrotal circumference, spermatozoal morphology, spermatozoal motility, a combination of inadequate spermatozoal morphology and motility, or physical abnormalities. Inadequate scrotal circumference or physical abnormality did not affect differences for BSE outcomes among systems. Using the SFT93 system, bulls failed at a higher rate due to inadequate spermatozoal morphology (P < 0.05) than when subjected to the SFT83 system. In the WC93 system, a higher percentage of bulls failed due to inadequate spermatozoal motility and to a combination of inadequate spermatozoal morphology and motility than in the other 2 systems (P < 0.05). The proportion of bulls in this data failing under the WC93 system appears to be the result of overestimation.

Breeding Soundness Evaluation of Yearling Bulls

Breeding Soundness Evaluations (BSEs) are a useful tool to improve reproductive performance and profitability in beef herds. Veterinarians providing this service must be thorough in their evaluation, especially in yearling bulls. The 1993 Society for Theriogenology guidelines for BSE provide appropriate standards for classifying yearling bulls; veterinarians are advised to adhere to these standards as minimums for classification of the satisfactory potential breeder.

Morphometric analysis of collagen in gestational and retained bovine placentomes

Bovine placentome collagen was quantified (P<0.01) at four gestational stages (90, 150, 210 and 270 d, n = 8 d ), at 2 h post partum without (n = 4) and at 2 and 12 h post partum with (n = 8) experimentally-induced placental retention. Placentome sections were fixed and stained for collagen. Fetal cotyledonary (FC) collagen volume fraction (V(V)) increased over days of gestation studied (V(V)=0.03+/-0.01, 0.06+/-0.01, 0.13+/-0.01 and 0.19+/-0.01). Fetal cotyledonary hydroxyproline (3.15+/-0.41, 4.55+/-0.41 and 7.04+/-0.41 mg/g) and FC protein (432.0+/-17.1, 479.9+/-17.1, 585.4+/-17.1 mg/g) increased over Days 90, 150 and 210 and were similar on Days 210 and 270. Fetal cotyledonary collagen V(V) and hydroxyproline did not differ between Day 270, retained and nonretained cotyledons. Protein concentration was higher in 2 h (578.1+/-18.5 mg/g) and 12 h (526.0+/-18.5 mg/g) retained versus nonretained (400.4+/-36.2 mg/g) cotyledons. Maternal caruncular (MC) collagen V(V) and protein concentration were higher on Days 90 and 150 than on Days 210 and 270. Maternal caruncular hydroxyproline was similar from Day 90 to 210 and increased from Day 210 to 270. Maternal caruncular collagen V(V), hydroxyproline and protein concentrations were similar on Day 270 and in 2 h and 12 h retained membrane caruncles. Gestational increases in placentome collagen occurred from FC sources. No difference in FC or MC collagen V(V) existed between Day 270, retained and nonretained placentomes.

Absence of uterokinetic effects of prostaglandin F2α on oxytocin-reactive uterus in the mare

Abstract In most cyclic females, prostaglandin F 2α (PGF 2α ) triggers a uterine motility response resembling that of oxytocin (OT). To determine if PGF 2α is a uterokinetic substance in the cycling mare, uterine motility was measured by intrauterine balloon technique in 12 conscious, normally cyclic mares. After 60 min of saline infusion, continuous intravenous (i.v.) infusion with OT (1 i.u./min) was followed by PGF 2α (200 μg/min) for 60 min each. The experiment was repeated 3 wk later except with PGF 2α preceeding OT. A second group of mares was administered OT (60 i.u.) either i.v., intramuscularly (i.m.), or intrauterinely (i.u.). Plasma samples were studied for progesterone concentration. Control uterine motility for the first group of mares was (mean ± SEM) 545.83 ± 45.10 mm 2 . Significant (P 2 ) regardless if PGF 2α preceded OT infusion or vice-versa. No significant difference (P>0.05) was seen in motility after PGF 2α (423.33 ± 31.12 mm 2 ) infusion. The uterokinetic effect of OT was greatest when OT was administered i.v. (1696.50 ± 195.46 mm 2 ) followed by i.m. (819.82 ± 39.96 mm 2 ), and it was least effective when administered i.u. (607.83 ± 21.56 mm 2 ) as compared to control uterine motility (279.78 ± 22.33 mm 2 ). Skin electrical resistance values rose from 0 to 2000 ohms with PGF 2α infusion (but not with OT), indicating that PGF 2α was bioactive. It was concluded that PGF 2α was not a uterokinetic substance in the cyclic mare.

Uterokinetic activity of fenprostalene (a prostaglandin F2α analog) in vivo and in vitro in the bovine

The luteolytic potency of fenprostalene (a PGF2alpha analog) is about 20-times that of naturally produced PGF2alpha. The objective of this research was to investigate the uterokinetic effects of fenprostalene at a luteolytic dosage (1.0 mg) in the cyclic and early postpartum cow, and in the isolated uterine horn. Uterine motility measurements were conducted on two consecutive days in each cow. Experimental protocol on Day 1 was: spontaneous motility was recorded for 1 h; fenprostalene was injected (1.0 mg i.m.), after which motility was recorded for 2 h; fenprostalene was injected (1.0 mg i.v.) and motility was recorded for 30 min; and oxytocin was injected (40 U i.v.), followed by a 30-min recording period. On Day 2, the treatment sequence was reversed: spontaneous motility was recorded for 1 h; oxytocin was injected (100 U i.m.), after which motility was recorded for 2 h; fenprostalene was injected (1.0 mg i.v.) and motility recorded for 30 min; and oxytocin was injected (40 U i.v.), followed by a 30-min recording period. In the in vitro experiment, different dosages of fenprostalene (5.9, 11.8, 17.6, and 29.4 ng/ml bath solutions) and oxytocin (0.06, 0.12, 0.18, and 0.60 mU/ml bath solutions) were tested in pairs for 1 h. The treatment was then repeated. In a different group, fenprostalene (5.9 ng/ml bath solution) and oxytocin (0.06 mU/ml bath solution) treatments were alternated. Fenprostalene (at luteolytic dosage) was not uterokinetic in either the cyclic or postpartum cow. However, fenprostalene and oxytocin had a significant uterokinetic effect (five- to six-fold pretreatment value) on the isolated uterine horn preparation at all dosages studied. Peak motility occurred between 10 to 15 min, followed by a gradual decrease to 40% at 60 min. When the treatments were repeated at 60 min, oxytocin but not fenprostalene caused a minute, transient contraction. However, fenprostalene-desensitized (by exposure to fenprostalene) uteri reacted significantly to oxytocin, and vice versa.

Clearance of exogenous carnitine in bovine semen: Potential diagnosis of epididymal function and patency of the ductus deferens

Carnitine content in the ejaculate depends mainly on the capability of the epididymis wall to transfer carnitine from the blood and on the patency of ejaculatory ductus systems. An elevation of carnitine in semen subsequent to an intravenous injection of carnitine is expected. Intravenous injections of carnitine (L-isomer and DL-isomers) caused a significant (P <0.05) elevation (more than 10-fold) in blood carnitine. However, carnitine injection failed to increase net secretion of carnitine into the ejaculate and blood elimination half-life was 2.3 hours. Mean concentrations of carnitine in the electroejaculate (3.0 nmoles/ml) were significantly lower than in the ejaculate following natural mating (180 nmoles/ml). Vasectomy decreased net carnitine per ejaculate to about 1/5 the prevasectomy value, when ejaculate was collected following natural mating. However, vasectomy did not affect carnitine concentrations in semen collected by electroejaculation. Twenty-one percent of the carnitine in semen originated in the accessory glands and 79% in the epididymides. Carnitine in the electroejaculate was originated almost exclusively in the accessory glands. It was concluded that the diagnostic value of carnitine in semen is limited. Some considerations are: secretion of carnitine is not organ specific, there are large individual variations, there is a negative effect of electroejaculation, and a carnitine loading dose technique is not feasible. However, there is a diagnostic potential in using carnitine assay to detect epididymides occlusion, but only when ejaculate is collected by an artificial vagina.