The effect of the spatial distribution of plant species within the sward on the searching success of sheep when grazing

The ability of grazing sheep to exploit preferred patches of grass species according to their spatial distribution was studied. The choices made by groups of four ewes in three cocksfoot ( Dactylis glomerata ) plots (80 × 80 m), in which 136 patches (30 × 30 cm) of perennial ryegrass ( Lolium perenne ) were either randomly distributed (plot Rand ) or grouped (plots Ag.1 and Ag.2 ) to create preferred feeding sites (four rich sites of twenty-five patches and four poorer sites of nine patches) were compared. On measurement days, each group was allocated to one of the three plots, and grazed it in at least four successive 30-min tests. At the end of the experiment the ewes were allowed to graze the plots continuously for 3 months to assess the medium-term effect of grazing sheep on the depletion rate of patches. Behavioural observations showed that, once the ewes had discovered a preferred feeding site in plots Ag.1 or Ag.2 , they frequently returned to it within a test and between tests, whereas they failed to learn the precise location of many isolated patches in plot Rand . Thus in 2 h of grazing, the ewes spent 0·40 more time feeding on perennial ryegrass when the patches were grouped than when they were randomly distributed, and perennial ryegrass depletion was greater in plots Ag.1 and Ag.2 than in plot Rand (0·193 vs. 0·105 of initial height). The richer sites were also more depleted than the poorer ones (0·209 vs. 0·152 of initial height). When the plots were continuously grazed, perennial ryegrass depletion remained greater in plots Ag.1 and Ag.2 than in plot Rand for at least 3 weeks. Hence the spatial distribution of patches can affect diet selection by sheep, and so probably their impact on grasslands.     

Identification of Apoptotic Bodies in Equine Semen

Apoptosis in the testis is required to ensure an efficient spermatogenesis. However, sometimes, defective germ cells that are marked for elimination during this process escape elimination in the testes, giving rise to ejaculates with increased percentages of abnormal and apoptotic spermatozoa and a high percentage of apoptotic bodies. Apoptosis markers in the ejaculate have been associated with low fertility, either in animals or humans. Therefore, the goal of this study was to investigate whether fresh equine semen contains apoptotic bodies [initially named Merocyanine 540 (M540) bodies] and to study the relationship between the quantity of these bodies and cell concentration, the volume of ejaculate, viability and motility. Moreover, we also studied whether the presence apoptotic bodies in fresh semen was related to the resistance of the stallion spermatozoa to being incubated at 37°C or being frozen and thawed. Fresh equine semen was stained with fluorescent dyes such as M540 and Annexin‐V. Active Caspase 3 was studied in fresh semen through Western blotting and immunofluorescence with a specific antibody. Sperm kinematics was assessed in fresh, incubated and thawed samples using computer‐assisted semen analysis, and viability was evaluated with the LIVE/DEAD Sperm Viability Kit. Overall, our results demonstrate for the first time the presence of apoptotic bodies in equine semen. The quantity of apoptotic bodies was highly variable among stallions and was positively correlated with Caspase 3 activity in fresh samples and negatively correlated with the viability and motility of stallion spermatozoa after the cryopreservation process.     

Colloid Centrifugation Selects Normal Spermatozoa from Polymorphic Bull Ejaculates: A Case Study

Semen from a Western Finncattle bull exhibiting a highly polymorphic spermiogram was processed by colloid centrifugation using Androcoll‐B, a species‐specific silane‐coated silica colloid. In the first experiment, Single Layer Centrifugation (SLC) was used to identify which density colloids were needed to separate different cell populations. Colloids of the two chosen densities were then used in a density gradient resulting in two sperm subpopulations, one containing nearly all normally sized spermatozoa and the other enriched for the macrocephalic spermatozoa. Microcephalic spermatozoa did not appear in either of the selected subpopulations. Using a combination of SLC and DGC with this species‐specific colloid, it was possible to separate the spermatozoa into different subpopulations, that is, a subpopulation containing nearly all normally sized spermatozoa, and another one enriched for the macrocephalic spermatozoa. Thus, colloid centrifugation could be used to select sufficient normal spermatozoa from a highly polymorphic ejaculate for AI, if desired.     

Anti‐Mullerian Hormone Concentration and Antral Ovarian Follicle Population in Murrah Heifers Compared to Holstein and Gyr Kept Under the Same Management

This study was performed to evaluate plasma concentrations of anti‐Mullerian hormone (AMH) and the ovarian antral follicle population (AFP) in different genetic groups. Cyclic heifers (13 Bubalus bubalis [Murrah]; 15 Bos taurus [Holstein] and 10 Bos indicus [Gyr]) were maintained under the same management and were synchronized with two doses of 150 μg IM d‐cloprostenol administered 14 days apart. After the second d‐cloprostenol treatment, heifers had their ovaries scanned daily by ultrasound to define the day of ovulation. On the same day, the AFP was determined and a plasma sample was collected to measure AMH. Murrah heifers had less AFP (25.6 ± 2.1 follicles; p = 0.01) and plasma AMH concentration (0.18 ± 0.03 ng/ml; p < 0.001) than Gyr (60.0 ± 12.2 follicles and 0.60 ± 0.12 ng/ml of AMH); however, data were similar when compared to Holstein (35.9 ± 6.8 follicles and 0.24 ± 0.06 ng/ml of AMH) heifers. Regardless of genetic background, there was a positive relationship between the AFP and plasmatic AMH concentration (Murrah [r = 0.62; p < 0.01], Holstein [r = 0.66; p < 0.001] and Gyr [r = 0.88; p < 0.001]). Also, when heifers were classified according to high‐ or low‐AMH concentration based on the average within each genetic group, high‐AMH heifers had greater (p < 0.0001) AFP than low‐AMH heifers. In conclusion, both Murrah and Holstein heifers presented lower plasma AMH concentration and AFP when compared to Gyr.     

Effect of Overnight Staining on the Quality of Flow Cytometric Sorted Stallion Sperm: Comparison with Tradtitional Protocols

Flow cytometry is considered the only reliable method for the separation of X and Y chromosome bearing spermatozoa in equines. The MoFlo SX DP sorter is highly efficient, allowing the production of foals of the desired sex. However, to achieve acceptable pregnancy rates the currently used protocol requires working with fresh semen obtained close to, or at, the sorting facility. An alternative protocol was tested during two consecutive breeding seasons. Fresh stallion semen was cooled for 20 h, during which staining with Hoechst 33342 took place. On the following day, this sample was flow sorted and compared with spermatozoa from the same ejaculate that had been sexed on the previous day. All sperm parameters evaluated remained unchanged when fresh sorted and refrigerated sorted semen were compared. Pre‐sorting storage at 5°C did not alter sperm velocities nor kinetics, viability or membrane permeability, production of reactive oxygen species, mitochondrial membrane potential or DNA fragmentation index of the sorted sample. The findings open for the possibility of using semen from stallions housed far from the sorting facilities. Processed and stained sperm could be shipped refrigerated on the previous day, sorted and inseminated on the next day.     

Standing Laparoscopic Peritoneal Flap Hernioplasty of the Vaginal Rings does not Modify the Sperm Production and Motility Characteristics in Intact Male Horses

Laparoscopic hernioplasty techniques have been developed in the recent years to avoid the recurrence of inguinal hernias and to spare the testicles for breeding purposes in stallions. However, there have been no previous comprehensive and systematic studies of the reproductive outcomes and prognoses for stallions after inguinal hernioplasty. Therefore, the objective of this study was to assess the possible effects of one of these techniques (standing laparoscopic peritoneal flap hernioplasty) on the sperm production and motility characteristics of six healthy stallions that received this procedure based on 1‐year follow‐ups. There were no significant differences in the measured sperm variables (assessments based on the DSO, MOT, PMOT, VSL, VCL and VAP) during 1‐year follow‐ups.