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Abstract

Objective—To study the effect of the reproductive state of female alpacas (ie, maiden [never bred before], barren [bred but failed to conceive or maintain pregnancy in previous breeding season], or gave birth and currently lactating) on embryonic mortality rate.

Animals—167 female alpacas (54 lactating, 44 barren, and 69 maiden) that ovulated following a single breeding.

Procedures—During the first 45 days following breeding, female alpacas underwent periodic transrectal ultrasonography to determine the presence or absence of an embryonic vesicle. Serum progesterone concentrations were determined during the same period. Embryonic survival rate was analyzed for each group of females (lactating, barren, and maiden).

Results—The presence of an embryonic vesicle or embryo was positively associated with high serum progesterone concentrations (> 2 ng/mL). The embryonic mortality rate in barren females (21/44 [47.7%]) was significantly higher than in maiden (20/69 [29.0%]) and lactating (16/54 [29.6%]) females. In females that underwent embryonic loss (n = 57), 3 patterns of events in terms of serum progesterone concentrations were identified: concomitant decrease of serum progesterone concentration and embryonic loss (24/57 [42.1%]), decrease in serum progesterone concentration before embryonic loss (12/57 [21.1%]), and persistent serum progesterone concentrations beyond embryonic loss (21/57 [36.8%]). Patterns of serum progesterone concentration and embryonic loss did not differ significantly among lactating, barren, and maiden female alpacas.

Conclusions and Clinical Relevance—Embryonic loss in alpacas occurred without any discernible pattern in serum progesterone concentrations. Barren female alpacas had the highest embryonic mortality rate. (Am J Vet Res 2010;71:1096–1099)

Restricted access
in American Journal of Veterinary Research

Abstract

Objective—To determine endometrial regeneration in postpartum mares by analysis of histologic features, apoptosis and cell proliferation markers, lectin binding, cytokines, and progesterone and estrogen receptors in endometrial biopsy specimens.

Animals—9 postpartum mares.

Procedures—Mares were examined on postpartum days 1, 9, and 16, and uterine biopsy specimens were obtained for histologic examination. Lectin binding was analyzed histochemically, and expressions of Ki-67 antigen (proliferation marker), lysozyme, and caspase 3 (apoptosis marker) were studied immunohistochemically. Gene expressions for cytokines (interleukin-1β, -6 and -8 and tumor necrosis factor-α), cyclooxygenase 2, prostaglandin-E-synthase, and estrogen and progesterone receptors were determined by use of quantitative real-time PCR assay.

Results—On day 1, neutrophils predominated but by day 9 had largely been replaced by lymphocytes and macrophages. High numbers of cells with staining for caspase 3 were found on day 1, but numbers decreased by day 9. In contrast, the number of cells with staining for Kiel 67 antigen increased between days 1 and 9. Lectin binding to the endometrium changed over time. Relative mRNA expressions for cytokines and prostaglandin-E-synthase did not differ among days. Expressions of progesterone and estrogen receptors were minimal on day 1 and increased by day 9.

Conclusions and Clinical Relevance—Early postpartum endometrial cells underwent apoptosis, but during the second week, postpartum proliferation of cells predominated. Lectin binding reflected changes in endometrial glycocalyx patterns. Increased expression of estrogen receptors allowed the endometrium to respond to estrogen during foal heat, and in subsequent diestrus, the endometrium was able to respond to progesterone.

Restricted access
in American Journal of Veterinary Research

Abstract

Objective—To define the optimum period for sexing of Saanen goat fetuses by use of transrectal ultrasonography.

Animals—82 Saanen goats pregnant with 124 fetuses.

Procedures—Fetal sexing was performed on the basis of the final location of the genital tubercle or identification of external genitalia. In experiment 1, fetuses (n = 78) were monitored every 48 hours from days 40 to 60 of gestation, whereas for experiment 2, 46 fetuses were examined only once between days 47 and 77 of gestation.

Results—For experiment 1, accuracy of fetal sexing was 20 of 20 (100%) for a single fetus, 39 of 42 (92.8%) for twin fetuses, and 10 of 16 (62.5%) for triplet fetuses. Diagnostic accuracy was significantly lower for triplet fetuses than that for single or twin fetuses. Final location of the genital tubercle was detected between 45 and 55 days of gestation (mean ± SEM, 48.9 ± 1.8 days). For experiment 2, accuracy of fetal sexing for a single fetus (24/24 [100%]) was significantly higher than the accuracy for twin fetuses (16/22 [72.7%]). Considering all fetuses that were born, accuracy of diagnosis was 69 of 78 (88.4%) for experiment 1 and 40 of 46 (86.9%) for experiment 2. Accuracy did not differ significantly between experiments.

Conclusions and Clinical Relevance—Real-time ultrasonography after day 55 of gestation is a suitable method for determination of sex of Saanen goat fetuses by observation of the genital tubercle or identification of external genitalia.

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in American Journal of Veterinary Research

Abstract

Objective—To identify the generation of the superoxide anion by equine spermatozoa.

Sample Population—Multiple ejaculates collected from 3 Thoroughbred stallions.

Procedures—Induced superoxide production by reduced nicotinamide adenine dinucleotides (NAD[P]H; ie, reduced nicotinamide adenine dinucleotide [NADH] and reduced nicotinamide adenine dinucleotide phosphate [NADPH]) was measured by use of a nitroblue tetrazolium (NBT) reduction assay on whole spermatozoa and a cytochrome c reduction assay on isolated membrane fractions of spermatozoa. Localization of superoxide generation was determined by use of NBT cytochemistry.

Results—A dose-dependent increase in NBT reduction was found in the presence of NADPH, which was inhibited by superoxide dismutase (SOD). The flavoprotein inhibitor, diphenyleneiodonium (DPI; 5 or 15μM), significantly decreased NBT reduction. Cytochrome c reduction by plasma membranes of spermatozoa was significantly higher in the presence of NADPH than in its absence. Cytochemical staining of equine spermatozoa in the presence of NADPH and NADH revealed diaphorase labeling in the spermatozoon midpiece and head. This staining was inhibited by DPI and SOD.

Conclusions and Clinical Relevance—Results of our study indicate that superoxide generation is associated with a membrane-associated NAD(P)H oxidase present in equine spermatozoa, although mitochondrial generation of superoxide is also detected. This oxidase may play a role in cell signaling or may also contribute to cytopathic effects associated with oxidative stress in equine spermatozoa.

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in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of a controlled-release monensin capsule administered at cessation of lactation on incidence of calving-related disorders, fertility, and milk yield in dairy cows.

Animals—290 dairy cows treated with monensin and 290 untreated control cows.

Procedure—Treated cows received a capsule that released monensin at 335 mg/d for 95 days. Incidence of calving-related disorders; daily milk yield up to 20 days postpartum; test-day milk yield, fat, protein, and mature-equivalent 305-day milk production; and body condition score at calving were determined. Reproductive variables were conception rate at first service, pregnancy rate, and calving-to-conception interval.

Results—Cows treated with monensin were 2.1 times as likely to develop dystocia and 0.8 times as likely to develop metritis as control cows. For milk yield, there was an interaction of treatment ×time ×parity. In multiparous cows, monensin significantly improved milk yield at test days 4 and 7. In addition, monensin increased body condition score at calving.

Conclusions and Clinical Relevance—Despite increasing the likelihood of developing dystocia and metritis, administration of monensin improved the lactational performance of multiparous cows and may be a promising additive for use at the time of cessation of lactation.

Restricted access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate Coomassie blue staining of the acrosome of equine and canine spermatozoa.

Sample Population—Spermatozoa of 5 mixed-breed male dogs and 3 Thoroughbred stallions.

Procedure—Various proportions of intact and acrosome-damaged spermatozoa were fixed in 2% phosphate-buffered formaldehyde or 4% paraformaldehyde, smeared onto glass slides, and stained with Coomassie blue stain. Acrosomal status (damaged vs intact) was also assessed by use of flow cytometry after staining with fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (FITC-PSA) and propidium iodide. Comparisons were made between percentages of expected and observed acrosome-intact spermatozoa in different proportions of live and flash-frozen samples; the percentages of acrosome-intact spermatozoa as determined by use of Coomassie blue staining and flow cytometry were also compared.

Results—Strong correlations were found between the expected and observed distributions of acrosome-intact spermatozoa when fixed in 4% paraformaldehyde (r = 0.93 and 0.89 for canine and equine spermatozoa, respectively) as well as between Coomassie blue-stained cells and those stained with FITC-PSA and assessed by use of flow cytometry (r = 0.96 and 0.97 for canine and equine spermatozoa, respectively). However, in canine samples that were fixed in 2% phosphate-buffered formaldehyde, these correlations were weak.

Conclusions and Clinical Relevance—Staining with Coomassie blue stain was a simple and accurate method to evaluate the acrosome in equine and canine spermatozoa after fixation in 4% paraformaldehyde. This assay should be useful in routine evaluation of semen samples from these species.

Restricted access
in American Journal of Veterinary Research