Clinical Theriogenology

Genomic selection in dairy cattle: impact and contribution to the improvement of bovine fertility

Kent Weigel — 2024-03-14

Genomic selection has revolutionized the dairy cattle breeding industry, with ripple effects that have greatly impacted dairy herd management. Rate of genetic progress has increased markedly, especially in Holstein and Jersey breeds, for production, health, and fertility traits. Genomic testing of young bulls and heifers provides greater accuracy of selection decisions involving traditional fertility traits, such as daughter pregnancy rate, while creating the opportunity to improve novel traits, such as fetal loss. Cameras, wearable sensors, and other precision livestock farming technologies will allow selection for traits such as estrus duration and intensity that require high frequency phenotyping. At the same time, synergies between genomic testing and advanced reproductive technologies have led to rapid and widespread adoption of sexed semen, coupled with mating of females whose offspring are not needed as herd replacements to beef sires. This strategy produces added-value crossbred calves for the beef supply chain, while allowing genetically inferior mature cows that are still producing at a high level to remain in the herd for additional lactations.

Congenital hydrocephalus in a stillborn Haflinger foal

Gail McRae — 2024-03-14

A 14-year, multiparous Haflinger mare, apparently fullterm (unknown breeding or ovulation date), was presented for dystocia. Mare was transvaginally palpated at the farm by the referring veterinarian; foal was in craniolongitudinal presentation, dorsosacral position with extended forelimbs in the vaginal vault and head just cranial to cervix, and a cranial abnormality of the foal prevented assisted vaginal delivery. Mare was referred. Foal was not alive at presentation and was undeliverable with assistance because of congenital hydrocephalus. Anesthetized mare was placed in Trendelenburg position, controlled vaginal delivery was elected and foal was removed via fetotomy. Mare was negative for β1, 3- N-acetylgalactosaminyltransferase 2 (B3GALNT2) nonsense mutation (reported to be responsible for hydrocephalus). Dystocia in a Haflinger mare because of hydrocephalus is reported for the first time.

Amorphus globosus

Kaylin McNulty — 2024-02-16

Amorphus globosus is a rare malformation that is defined as an acardiac asymmetrical rough spherical mass of tissue covered in skin. To authors’ knowledge, amorphus globosus has not been previously reported in canids. Herein, we describe amorphus globosus in an American Bulldog pup with accompanying radiograph, gross images, and histopathology. Additionally, a systematic review (preferred reporting items for systematic reviews and meta-analyses protocol) was performed for veterinary species; amorphus globosus has been reported in 22 bovids, 3 caprids, 1 ovid, and 1 equid.

Disorders of sexual development in small ruminants

Joaquin Paredes — 2024-01-23

Intersex conditions, also known as disorders of sexual development (DSD), are uncommon in small ruminants. This report describes in detail, 2 cases of DSD in small ruminants, including clinical presentation, histopathological and cytogenetic analysis that led to the final diagnoses. Case 1, a mixed-breed ewe, was assessed due to a reported ram-like behavior at ~ 6 months of age. Physical examination revealed abnormal external genitalia with enlarged clitoris and bilateral inguinal gonads, histologically confirmed as testicular tissue. Karyotyping revealed sex chromosome blood chimerism (54XX, 54XY), implicating freemartinism as the cause of DSD. Case 2 was a 1-year Nigerian Dwarf cryptorchid male goat presented for castration. During surgery, bilateral ovoid gonads attached to a bicornuate uterus were identified. Histology revealed testicular tissue and uterus alongside vas deferens were consistent with persistent Müllerian duct syndrome. This report describes presentations, findings, and features of DSD, a rare occurrence in small ruminants.

Modified diff-quick staining for canine sperm morphology

Mariana Mazzuchini — 2024-02-16

Sperm morphology assessment requires specialized microscopes or stains. Diff-quick (DQ) is considered a universal stain that is cost-effective; however, morphological evaluation of sperm using DQ staining is poor and not encouraging. Therefore, this study investigated modifications to the DQ protocol to improve identification of morphological defects of dog sperm and compared the modified DQ techniques with eosin-nigrosin, Karras, and differential interference contrast microscopy [DIC]). One ejaculate from each of 9 dogs was used. To perform the proposed modified DQ techniques (DQ1 and DQ2), dried semen smears were fixed by immersing for 10 seconds in solution 1 of DQ and 5 minutes each in solutions II and III of the kit. After the third stain solution, slides in DQ1 were rinsed in water whereas slides in DQ2 were not rinsed but were vertically supported to facilitate stain drainage. Results suggested that the standard DQ protocol overestimated normal sperm and detached heads whereas underestimated abnormal heads and total defects compared to DIC, Karras, eosin-nigrosin, and DQ2. Acrosome abnormalities were only detectable with Karras, DIC, and DQ2. In conclusion, prolonging exposure to DQ staining solutions enhanced sensitivity in sperm morphological evaluation, and avoiding rinse as a final step in the DQ protocol improved visualization of certain acrosome defects in dog sperm. Therefore, modified DQ techniques can serve as a viable alternative for dog sperm morphology evaluation in clinical practice.

Effects of bovine ova density and culture supplements on cleavage and blastocyst development rates of in vitro embryos

Jessica Looman — 2024-02-02

An optimized in vitro culture system is important to maximize bovine blastocyst development. Four experiments were conducted to explore manipulation of culture environments and investigate the benefits of culturing embryos in groups. Follicles were aspirated from abattoir-derived ovaries and selected oocytes were matured, fertilized, vortexed, and randomly placed in culture groups. Experiment 1 evaluated the effects of ova culture density on blastocyst development among embryos cultured individually or in groups of 5, 10, 20, or 50 embryos. Experiment 2 evaluated the effects of conditioned media from previous replicates on embryo development of the current culture. In Experiment 3, cleaved embryos were grouped together after being in culture for 24 hours. Lastly, in Experiment 4, grouped embryos were placed in 10 μl culture drops to evaluate the effect of high density/low media volume on development. Cleavage and blastocyst rates analyzed via Chi-square indicated that although cleavage rates were similar among culture groups (and experiments), blastocyst development was lower (p < 0.05) in 1 embryo culture group compared to other groups. When conditioned culture media from previous replicates were added to original culture media, blastocyst development was similar among original and conditioned culture groups of 20 and 50 embryos. When cleaved embryos were amalgamated and cultured, blastocyst development was higher (p < 0.05) in culture groups of 10 than 1 cleaved embryo groups but similar to controls for both culture groups. When embryos were cultured in 10 μl drops, embryos cultured in groups of 5 had lower development to blastocysts compared to groups of 2, 10, 25, and control. In conclusion, these data indicated an apparent ‘helper effect’ expressed in culture environments of groups, and this effect apparently occurred after cleavage but before blastocyst development. Direct or indirect role(s) that additional cells have on in vitro culture and the mechanism of this helper effect requires further investigation.

Effect of incorrect storage of bull semen samples on sperm morphology assessment

Allan Gunn — 2024-02-01

Thirteen pairs of bull semen samples were assessed. One of each pair of samples was inadvertently stored in phosphate buffered saline (PBS) that was used for analysis of motility immediately after collection. Other sample of the pair that was correctly stored in buffered formol saline (BFS) was assessed later. Proportion of morphologically normal sperm was different (p = 0.0021) between the 2 storage methods. Most of the abnormalities in the PBS samples were loose and detached heads. Closer examination of these sperm illustrated changes in the composition of the tail, with an apparent loss of the plasma membrane. This serendipitous error allowed documentation of the importance of correct storage of semen samples for morphological assessment of sperm, and the tertiary defects detected with the incorrect storage of semen samples in semen extender. Tertiary defects should always be considered a possibility during morphological assessment of sperm via spermiogram.

Stallion sperm concentration measurements: experience and equipment

Dale Kelley — 2024-01-22

Accuracy is paramount in evaluating sperm concentration and can be a challenge to those with minimal laboratory experience. Purpose of the study was to determine the effect of operator experience on sperm concentrations using 4 methods: Makler^® counting chamber, equine densimeter, iSperm, and NucleoCounter^®. There was no difference (p = 0.64) between experienced and novice processors for Makler^® counting chamber; was difference (p = 0.005) for equine densimeter; was no difference (p = 0.35) for iSperm; and was tending toward difference (p = 0.068) for NucleoCounter^®. Correlation between bias and magnitude for Makler^® counting chamber was –0.74 (p = 0.003); for equine densimeter was –0.44 (p = 0.11); for iSperm was 0.06 (p = 0.83), and NucleoCounter^® was –0.52 (p = 0.06). Makler^® counting chamber produced a mean sperm concentration similar to an experienced processor but had significant variation within novice processors. Equine densimeter significantly overestimated sperm concentrations with novice processors but had the least variation. The iSperm performed poorly for both experienced and novices and produced significantly different concentrations than other methods. Thus, iSperm cannot be recommended to accurately measure sperm concentration. Lastly, NucleoCounter had no difference in mean sperm concentrations or variation and was the best system for a novice processor to gain accurate and repeatable sperm concentration measurements.