Reproductive response of crossbred Bos taurus × Bos indicus cows to biostimulation by pre-pubertal and pubertal teasers.

Although the beneficial effect of biostimulation on reproduction has been reported, the influence of selectivity and social factors on the response to biostimulation has not received sufficient research attention in both Bos indicus and Bos indicus influenced cattle. Furthermore, 'green and cheap' strategies to improve cattle reproduction are currently in demand while Bos indicus influenced cattle with inferior reproductive performance, and farmers with economic limitations are common in tropical zones. Hence, to assess the reproductive response of crossbred taurus × indicus cows to biostimulation by pre-pubertal (PPM) or pubertal (PM) teasers males, two trials of 2 years each were conducted. Trial 1 n = 187 cows (Year 1:85 cows exposed to PPM and Year 2:102 cows exposed to PM). Trial 2 n = 196 cows (Year 1:101 cows exposed to PPM and Year 2:95 cows exposed to PM). The effect of exposing cows to PPM and PM on the intervals calving to first service (ICFS), calving to conception (ICC) and economic cost of days open (ECDO) was analysed using Kruskal-Wallis ANOVA and the effect of exposing cows to PPM and to PM on reproductive status at 90 days (RS90) and proportion of cows requiring hormonal protocols (PRH) was compared using χ2 analysis. Both ICFS and ICC were shorter (p < .0001) for PM-exposed females (96.12 ± 4.1 and 110.93 ± 2.9 days; respectively) compared with those PPM-exposed (134.41 ± 3.3 and 135.64 ± 2.4 days; respectively). With RS90, more (p < .0001) PM-exposed cows (50.7%) were pregnant compared with PPM-exposed cows (16.1%). The PRH was greater (p < .0001) in PPM-exposed cows (79.0%) compared with PM-exposed (27.9%). The ECDO was less (p < .0001) in PM-exposed cows (US$ 142.9 ± 3.8) compared with PPM-exposed (US$ 176.3 ± 2.9). In conclusion, cows exposed to PM had shorter ICFS and ICC compared with cows exposed to PPM. More cows exposed to PM were pregnant after 90 days, and PRH was less than cows exposed to PPM. Cows exposed to PM had a reduced ECDO than those exposed to PPM.

Biostimulation and pheromones in livestock: A review.

This review examines aspects of the phenomenon of biostimulation in swine, goats, sheep, cattle and deer, to improve the collective knowledge and exploitation of its relevant mechanisms and effects in animal production. The long-term goal is to implement biostimulation strategies that benefit livestock reproduction and production while being both cost-effective and socially acceptable.

Prospects for increasing the utilization of cattle embryo transfer by small-scale milk and meat producers in tropical regions.

Small community cattle farmers in the tropics are facing challenges to deliver quality products whilst under pressure to increase milk and beef yields per cow. These challenges could be partially met by crossbreeding Bos taurus with Bos indicus (F1) cattle utilizing embryo transfer (ET) technology. The Bos taurus infusion would increase milk production, whilst the Bos indicus influence can improve resistance to the harsh environment of the tropics. Here, individuals from existing herds can be used to produce F1 embryos which benefit from hybrid vigour. Resultant female offspring would in turn receive an F1 embryo on reaching breeding maturity. This approach would help to provide a cost-effective, systematic approach to improve productivity in dairy and beef cattle in the tropics. However, full usage of ET, including in vitro applications, in the tropics will require improvements in procedures, resources and education.

Effect of season and genotype on values for bull semen variables under tropical conditions.

To assess the effects of season and genotype on fresh semen quality for freezing and subsequent use for AI, 32 healthy, mature (>4 to <6 years old) and habituated bulls (Bos indicus n = 14, Bos taurus n = 5, Crossbred taurus x indicus n = 6, and tropically adapted Bos taurus composites n = 7) were evaluated at a Venezuelan AI center for 12 months in which four distinct seasons (Hot-dry, Transition, Hot-humid, Cool-rainy) occur. Ejaculates were collected weekly from Bos taurus (n = 260), Bos indicus (n = 669), tropically adapted Bos taurus composites (n = 389), and crossbred Bos taurus x Bos indicus (n = 340) bulls. Routine AI Center assessments were conducted i.e., ejaculate volume (EV), sperm mass-motility (MM), total sperm number/ejaculate (TSE), sperm concentration/mL (SC), pre-freezing (PREF), and post-freezing minimum criteria rate for AI use (POSTF). Genotype affected EV (P < 0.0001), TSE (P < 0.0001), and SC (P < 0.0001) but not MM (P>0.05). Season affected EV (P < 0.001), TSE (P < 0.0001), SC (P < 0.01), and MM (P < 0.05). There were genotype x season interactions for EV, MM, TSE, and SC. The PREF averaged 74.0% during the study, although was less (P < 0.0001) during the hot-humid season than the other seasons. Even though, percent ejaculates considered unsuitable for freezing differed (P < 0.03) among the Hot-dry (20.2%), transition (30.9%), Hot-humid (32.4%), and Cool-rainy (24%) seasons. For POSTF, there were no seasonal differences (P>0.05). It is concluded that in tropical regions, season and genotype can affect bull semen variables, particularly those which affect the success of semen freezing and AI.

About the inconvenience of handling mixed-breed herds; aspects of social behavior as a potential source of stress and economic losses.

The objective of this study was to assess aspects of the social behavior of a mixed-breed herd of beef cows as a potential source for stress and economic losses. Angus (AN; N = 10), Brahman (BR; N = 10), and Senepol (SE; N = 10) cows were assigned to two groups (N = 15 each containing equal breed numbers) on separate pastures. Agonistic interactions (win/loss) during feeding were recorded daily for 45 days. Dominance values were estimated as the proportion of individuals dominated to total herdmates. From this, individuals were placed into social categories based upon linear ranking as follows: dominants (D), intermediate (I), and subordinates (S). Breed influenced (P < 0.01) social category, with SE cows being dominants (P < 0.05) over AN and BR cows. Interactions between AN and BR cows were less (P < 0.0005) than interactions between AN and SE (53 vs 140, respectively). Within breeds, BR (152) and SE (182) cows had more (P < 0.0005) agonistic interactions than AN (107) cows. Although apparently influenced by breed, agonistic interactions occurred more frequently (P < 0.005) between social categories than within social categories (814 vs 310, respectively). Dominant cows were involved in more agonistic interactions with cows from different social categories than were intermediate and subordinate cows (P < 0.0005). However, intermediate (100) and subordinate (157) cows generated more (P < 0.0005) agonistic interactions within their own social category than dominant cows (53). It was concluded that, in mixed-breed herds, breed influences both social organization and agonistic interactions which could be considered as potential sources of stress and economic losses.

Andrology laboratory review: Evaluation of sperm concentration.

This article is the result of the work of the andrology task-force of the Association of Applied Animal Andrology, American College of Theriogenologists, European College of Animal Reproduction, Society for Theriogenology, and National Association of Animal Breeders. It is intended to serve as a comprehensive reference on methods to evaluate sperm concentration and to contribute to the adoption of best practices in veterinary andrology laboratories. The information covered in the article includes sample preparation and the use of manual counts, spectrophotometers, computer-assisted semen analysis, NucleoCounter, and flow cytometry. Emphasis is given to the principles of the methods and equipment, performing the evaluation, and common mistakes and/or pitfalls. In addition, the precision and accuracy of the different methods are also discussed.

Effects of bee venom treatment on growth performance of young pigs.

This study examined the effect of whole bee venom (BV) as a potential stimulant of the piglet immune system, on growth performance, blood parameters, plasma protein and immune globulin content of serum. Piglets (n = 97) received combinations of 0.5, 1.0, 1.5, 2.0 and 2.5 mg/kg of parenterally administered BV on 4 occasions between birth and Day 30. In the apipuncture group (n = 31), piglets were acupunctured with the worker honeybee. Two acupoints, GV-1 (Jiao-chao) and GV-20 (Bai-hui), were selected for apipuncture. All piglets (n = 128) in the treatment groups were treated 4 times throughout the study period of 60 days. The control piglets received no treatments. Blood was taken via jugular venipuncture on Day 30 after birth. Body weight and survivability were measured, and changes in hematological values were analyzed. Both the BV injection group and apipuncture group increased body weight and survivability by 26.6% and 21.8%, and 7.9% and 6.7% respectively compared to the controls. The numbers of leukocytes, erythrocytes, lymphocytes and monocytes were not influenced by treatments. However, a potential clinical benefit of high dose therapy was seen in increased populations of leukocytes, lymphocytes and monocytes compared with either the apipuncture or control groups. Other blood parameters such as total protein and albumin were not affected by treatment. However, IgG levels were generally higher in treated groups than in the controls. These findings indicate that BV might be useful to stimulate immuno-competence in pig production, possibly via the primary bioactive components of melittin, phospholipase A(2) and apamin. The administration of BV, either via injection or acupuncture, did not make any differences in growth performance of young pigs. These results would be useful for further purification and characterization of immune boosting agents from BV.

Efficacy of training in theriogenology as determined by a survey of veterinarians.

OBJECTIVE: To determine whether veterinarians perceive that theriogenology training at veterinary medical schools in North America and the Caribbean is adequate for achievement of theriogenology skills commonly used in private practice. PROCEDURES: A survey was mailed to members of the veterinary medical associations of Alabama, Kansas, Pennsylvania, and Washington. With regard to reproductive procedures in bovine, equine, porcine, small ruminant, camelid, and small animal species, veterinarians (predominantly practitioners) were asked to rate the importance of that procedure in their job and to assess their own degree of competency in that procedure at the time of their graduation from veterinary school. RESULTS: Procedures considered most valuable in practice were those that represent basic theriogenology education and training, such as transrectal palpation of cows and mares and interpretation of vaginal cytologic specimens in bitches. Dystocia management was a high priority in all species. Correlations between rankings for value in practice and competency at graduation were good, varying from 0.75 in cattle and 0.78 in horses to 0.98 in dogs and 1.0 in cats, small ruminants, and pigs. CONCLUSIONS: Analysis of these data suggests that appropriate theriogenology procedures are being taught in veterinary medical schools but perhaps not to the extent required to achieve adequate competency immediately at graduation. Issues requiring further investigation include the effect of tracking in the veterinary curriculum on theriogenology training, methods by which more students could receive greater practical exposure during theriogenology training, and the apparent relative lack of theriogenology training (including contraception) in small animals and exotic animals.

Availability of theriogenology training at North American and Caribbean veterinary colleges.

A survey of the veterinary colleges in North America and the Caribbean was undertaken to determine the extent of availability of theriogenology training. Didactic training in at least one species was required at all schools that responded to the survey. Laboratory experience in at least one species was required by 75.0% and clinical theriogenology experience in at least one species by 72.7%. The mean number of board-certified or board-eligible theriogenology faculty did not vary between 1995 and 2005, but there was a decrease in the number of such faculty at 57.2% of the schools that responded to the survey.

Mentoring within the veterinary medical profession: veterinarians' experiences as proteges in mentoring relationships.

Veterinary medicine professionals have recognized the importance of enhancing mentoring of students, as recruitment and retention of students have become prominent concerns. The purpose of the present study was to examine the form and degree of mentoring experienced by practicing veterinarians, as well as to seek to understand the factors that influence effective mentoring relationships. Data concerning their own experiences with mentoring relationships were gathered from practicing veterinarians. Results suggest that most practicing veterinarians had mentors and that the most frequent and effective mentors were initial employers, followed by teachers and advisors. Behaviors aimed at career development and socio-emotional support correlated highly with the perceived effectiveness of the relationship. Perceived similarity between the protege and the mentor also predicted effectiveness. These results are discussed as they relate to veterinary education.

Genetic sperm defects.

Genetic sperm defects are specific sperm defects, which have been shown to have a genetic mode of transmission. Such genetic linkage, either direct or indirect, has been associated with a number of sperm defects in different species, with this number increasing with improved diagnostic capabilities. A number of sperm defects, which have proven or suspected genetic modes of transmission are discussed herein, with particular emphasis on cattle. These include: 1. Acrosome defects (knobbed, ruffled and incomplete); 2. Head defects (abnormal condensation, decapitated, round head, rolled head, nuclear crest); 3. Midpiece abnormalities ("Dag" defect, "corkscrew" defect, "pseudo-droplet" defect); 4. Tail defects ("tail stump" defect, primary ciliary dyskinesia).

Environmental, genetic and social factors affecting the expression of estrus in beef cows.

Genetic, social and environmental factors affecting behavioral estrus were evaluated in Angus (n = 10), Brahman (n = 10) and Senepol (n = 10) cows during a PGF2alpha synchronized estrus and subsequent spontaneous estrus. Cows were equally stratified by breed to two groups of 15. Both groups were pre-synchronized with a modified two-injection PGF2alpha protocol. At the start of the experiment, cows were treated with 25 mg PGF2alpha followed by a second and third administration of 12.5 mg PGF2alpha, 11 and 12 days later to induce synchronized estrus. The subsequent estrus was designated as spontaneous estrus. Behavioral estrus data including the onset and end of estrus, estrous duration and the total number of mounts received for the synchronized and spontaneous estruses were collected using HeatWatch". Interval from the third PGF2alpha, treatment to the onset of a HeatWatch" estrus occurred earlier (P < 0.05) in Angus (31 +/- 5 h) than Brahman (53 +/- 7 h) or Senepol (53 +/- 4 h) cows, with dominant Senepol and Brahman cows taking longer to exhibit estrus after PGF2alpha than subordinate cows. The duration of the synchronized estrus tended to be shorter (P < 0.06) in Senepol (12 +/- 3 h) than in Angus (19 +/- 2 h) or Brahman (17 +/- 2 h) cows. Behavioral estrus data between the two periods were confounded by greater temperature-humidity index (THI) values during spontaneous estrus. The THI during spontaneous estrus appeared (P = 0.09) to affect the duration of estrus (9 +/- 1 h versus 16 +/- 1 h) and did affect (P < 0.0001) the total number of mounts received (8 +/- 4 mounts versus 34 +/- 4 mounts) during spontaneous estrus compared to synchronized estrus. Breed had no effect (P > 0.10) on the duration and total number of mounts received during synchronized and spontaneous estruses. In conclusion, type of estrus (synchronized or spontaneous), THI, social dominance and breed exerted significant effects on characteristics associated with behavioral estrus in beef cattle in subtropical environments.