Plasma fatty acid profile in Italian Holstein-Friesian dairy cows supplemented with natural polyphenols from the olive plant Olea Europaea L

This study evaluated the effects of supplementing with natural functional feed on the plasma fatty acid profile of lactating Italian Holstein-Friesian dairy cows. Thirty cows in mid-lactation received the natural olive extract PHENOFEED DRY (500 mg/cow/day) which mainly comprises hydroxytyrosol, tyrosol and verbascoside. The total content of polyphenols and the antioxidant power of standard feed, enriched feed and pure extract was evaluated respectively by Folin-Ciocalteu and DPPH assay, and a characterization in HPLC-UV (High-Performance Liquid Chromatography-Ultraviolet) of bioactive molecules present in the extract PHENOFEED DRY was performed. PHENOFEED DRY was provided for 60 days, and the plasma profile of fatty acids was determined by Gas Chromatography. The administration of enriched feed resulted in an increase in the ratio of Omega-6 to Omega-3 polyunsaturated fatty acids from 3:1 to 4:1 (p<0.001). This was not influenced by the calving order. The addition of polyphenols helped to keep monounsaturated (MUFA) and saturated (SFA) levels constant and results in a significant increase in polyunsaturated (PUFA) fatty acid after 15 days of administration. The Omega-6/Omega-3 ratio was in the optimal range. The findings show that inclusion of natural functional food such as plant polyphenols helps to maintain a healthy blood fatty acid profile in lactating dairy cows.

Incorporation of Testicular Ultrasonography and Hair Steroid Concentrations in Bull Breeding Soundness Evaluation

Testicular ultrasonography and steroid concentrations (cortisol, dehydroepiandrosterone sulfate (DHEA-S), cortisol/DHEA-S ratio, testosterone) in hair were examined for their utility in the bull breeding soundness evaluation (BBSE). Beef and dairy bulls (n = 16; 2.7 ± 0.4 years old; body condition score 3.2 ± 0.1) of five breeds were maintained under the same conditions at an accredited semen collection center. Bulls underwent routine semen collection twice weekly for 12 weeks and semen was processed and cryopreserved. Ultrasonography and hair sampling were undertaken at the last semen collection. Bulls with homogeneous testicular parenchyma (n = 8) had a higher (p < 0.05) percentage of motile sperm post-thawing compared with bulls with heterogeneous parenchyma (n = 8). There were no differences (p > 0.05) in the hair concentrations of cortisol, DHEA-S, and testosterone between bulls with homogeneous and heterogeneous parenchyma. In bulls with homogeneous parenchyma, hair DHEA-S concentration was positively correlated with percentage motile sperm (R² = 0.76), progressively motile sperm (R² = 0.70), and motility yield (R² = 0.71). The findings indicate that the integration of testicular ultrasonography and hair DHEA-S status in the BBSE could provide a more comprehensive assessment of indicative fertility in bulls. Additionally, ultrasonography can be used in the BBSE when the evaluation of semen parameters is not available.

Plasma metabolomics reveals major changes in carbohydrate, lipid, and protein metabolism of abruptly weaned beef calves

¹H NMR-based metabolomics was used to study the effect of abrupt weaning on the blood metabolome of beef calves. Twenty Angus calves (258 ± 5 kg BW; 5 to 6 months old) were randomly assigned to a non-weaned (NW) group that remained grazing with their dam or a weaned (W) group that underwent abrupt separation from their dam to a separate paddock on d 0 of the study. Body weight, behaviour, and blood samples for cortisol and metabolomics were measured at d 0, 1, 2, 7, and 14 of the study. On d 1 and 2, W calves spent less time grazing and ruminating, and more time vocalising and walking, had a greater concentration of cortisol, NEFA, 3-hydroxybutyrate, betaine, creatine, and phenylalanine, and lesser abundance of tyrosine (P < 0.05) compared to NW calves. Compared to NW calves at d 14, W calves had greater (P < 0.01) relative abundance of acetate, glucose, allantoin, creatinine, creatine, creatine phosphate, glutamate, 3-hydroxybutyrate, 3-hydroxyisobutyrate, and seven AA (alanine, glutamate, leucine, lysine, phenylalanine, threonine and valine) but lesser (P < 0.05) relative abundance of low density and very low-density lipids, and unsaturated lipids. Both PCA and OPLS-DA showed no clustering or discrimination between groups at d 0 and increasing divergence to d 14. Blood metabolomics is a useful tool to quantify the acute effects of stress in calves during the first 2 days after abrupt weaning, and longer-term changes in carbohydrate, lipid and protein metabolism due to nutritional changes from cessation of milk intake and greater reliance on forage intake.

Review: Development, adoption, and impact of assisted reproduction in domestic buffaloes

The domestic buffalo (Bubalus bubalis), also known as water buffalo, comprises two sub-species the River buffalo (B. bubalis ssp. bubalis; 50 chromosomes) and the Swamp buffalo (ssp. carabanensis; 48 chromosomes). Domestic buffaloes are a globally significant livestock species. In South Asia, the River buffalo is a primary source of milk and meat and has a very important role in food security. The River buffalo also supports high-value, differentiated food production in Europe and the Americas. The Swamp buffalo is an important draft animal and a source of food in Southeast Asia and East Asia. The growing importance of buffaloes requires that they undergo an accelerated rate of genetic gain for efficiency of production, product quality, and sustainability. This will involve the increased use of assisted reproduction. The initial application of reproductive technology in buffaloes had variable success as it relied on the adoption of procedures developed for cattle. This included artificial insemination (AI), sperm cryopreservation, and embryo technologies such as cloning and in vitro embryo production (IVEP). Reproductive technology has been progressively refined in buffaloes, and today, the success of AI and IVEP is comparable to cattle. Ovarian follicular superstimulation (superovulation) combined with in vivo embryo production results in low embryo recovery in buffaloes and has limited practical application. The contribution of elite female buffaloes to future genetic improvement will therefore rely mainly on oocyte pickup and IVEP. This will include IVEP from females before puberty to reduce generation intervals. This review provides for the first time a clear chronology on the development, adoption, and impact, of assisted reproduction in domestic buffaloes.

Impact of oocyte donor age and breed on in vitro embryo production in cattle, and relationship of dairy and beef embryo recipients on pregnancy and the subsequent performance of offspring: A review

Genomic selection combined with in vitro embryo production (IVEP) with oocytes from heifer calves provides a powerful technology platform to reduce generation interval and significantly increase the rate of genetic gain in cattle. The ability to obtain oocytes with developmental competence from calves has been recognised for more than 60years. There is renewed interest in the potential of this reproductive technology as the beef and dairy industries seek to identify and multiply animals that satisfy consumer demand for efficient utilisation of natural resources, with minimal environmental impact and high product quality. Heifer calves show a good follicular response to FSH stimulation and oocytes can be recovered by ovum pick-up (OPU). However, the efficiency of OPU/IVEP remains lower for calves compared with peripubertal heifers and cows, in both indicus (Zebu, Bos indicus ) and taurus (Bos taurus ) breeds. Indicus cattle generally have more follicles, yield a greater number of oocytes, and have a better IVEP outcome, compared with taurus cattle. The treatment of prepubertal heifers with bovine somatotrophin (bST) and propylene glycol before OPU/IVEP has yet to show a major improvement in embryo production. Holstein (taurus) dairy heifers derived from different reproductive technologies (AI, MOET, OPU/IVEP) showed a similar age at puberty and first-lactation milk production. OPU/IVEP Holstein embryos transferred to beef or dairy cows likewise yielded heifers with the same performance. The gains in productivity that can be achieved with strategic use of OPU/IVEP in heifer calves make this a relevant and highly important reproductive technology in cattle breeding. Ongoing optimisation of the technology is needed for the potential of OPU/IVEP in young donors to be fully realised.

Local action of cytokines and immune cells in communication between the conceptus and uterus during the critical period of early embryo development, attachment and implantation - Implications for embryo survival in cattle: A review

Early embryo development, implantation and pregnancy involve a complex dialogue between the embryo and mother. In cattle this dialogue starts as early as days 3-4 when the embryo is still in the oviduct, and it continues to implantation. Immunological processes involving cytokines, mast cells and macrophages form an important part of this dialogue. Amongst the cytokines, interleukin-6 (Il-6) and leukemia inhibitory factor (LIF) are secreted by both the embryo and uterine endometrium and form part of an ongoing and reciprocating dialogue. Mast cells and macrophages populate the uterine endometrium during embryo development and are involved in achieving the correct balance between inflammatory and anti-inflammatory reactions at the uterus that are associated with embryo attachment and implantation. Embryo loss is the major cause of reproductive wastage in cattle, and livestock generally. A deeper understanding of immunological processes during early embryo development will help to achieve the next step change in the efficiency of natural and assisted breeding.

Changes in the blood metabolome of Wagyu crossbred steers with time in the feedlot and relationships with marbling

Wagyu crossbred steers (n = 167) were used to (1) compare the metabolome of individual animals at two distant time-points (days 196 and 432) in a feedlot (this corresponded to 272 and 36 days before slaughter); and (2) determine relationships between the metabolome and marbling, and the effect of days in the feedlot (time-points) on these relationships. ¹H NMR spectroscopy followed by standard recoupling of variables analysis produced 290 features or 'peaks' from which 38 metabolites were identified. There was a positive correlation between the relative concentration (RC) at days 196 and 432 for 35 of 38 metabolites (P > 0.05). The RC of 21 metabolites mostly involved in muscle energy and glucose metabolism increased (P < 0.05) from day 196 to 432, and the RC of 13 metabolites mostly involved in lipid metabolism decreased (P < 0.05). There were 14 metabolites correlated with marbling including metabolites involved in energy and fat metabolism (glucose, propionate, 3-hydroxybutyrate, lipids). The relationship between marbling and the RC of metabolites was affected by time-point, being positive for 3-hydroxybutyrate and acetate (P < 0.05) at day 432 but not at day 196. The findings indicate that the blood metabolome in Wagyu crossbred steers changes with time in a feedlot. Notwithstanding, the metabolome has potential to predict marbling in Wagyu. The ability to predict marbling from the blood metabolome appears to be influenced by days in a feedlot and presumably the stage of development towards a mature body conformation.

Treatment with estradiol cypionate at progesterone withdrawal reduces handling without compromising the pregnancy rate to timed-AI in buffalo

The aim of this study was to determine if treatment with estradiol cypionate (EC) at the time of P4 withdrawal induced ovulation in a synchronization/timed-AI (TAI) protocol in buffalo. In Experiment 1, 56 buffaloes received an intravaginal P4 device (1.0 g) plus estradiol benzoate (EB, 2.0 mg im) on Day 0 (D0). On Day 9, the P4 device was removed and buffaloes were given PGF_2α (0.53 mg im sodium cloprostenol) plus eCG (400 IU im). Buffaloes were then randomly allocated to one of two groups: Group GEC (n = 29), treated with EC (1.0 mg im) at P4 device removal; Group GEB (n = 27), treated with EB (1.0 mg im) 24 h after P4 device removal. Ovarian ultrasound was undertaken on: D0, to ascertain general ovarian status; D9 to D11 (every 24 h), to measure diameter of the largest follicle (LF) and follicular growth rate; D11 to D13 (every 12 h for 72 h), to determine the time of ovulation and ovulation rate. Following P4 device removal, Groups GEC and GEB had a similar follicular growth rate (0.9 ± 0.1 and 1.1 ± 0.1 mm/day, respectively; P = 0.15) and similar LF diameter on D11 (11.4 ± 0.6 and 12.5 ± 0.5 mm; P = 0.12). Groups GEC and GEB also had a similar diameter of the ovulatory follicle (13.0 ± 0.5 and 13.4 ± 0.6 mm; P = 0.52), interval from P4 device removal to ovulation (68.2 ± 2.8 and 71.1 ± 1.4 h; P = 0.41) and ovulation rate (62.1% and 70.4%; P = 0.44). In Experiment 2, 199 buffaloes were assigned to the two treatments in Experiment 1 (GEC, n = 100; GEB, n = 99). All animals underwent TAI 56 h after P4 device removal and pregnancy diagnosis was preformed on D41. The pregnancy rate was similar for Groups GEC and GEB (50.0 and 45.5%, respectively; P = 0.45). The findings indicate that treatment with EC at the time of P4 withdrawal induces ovulation and achieves the same pregnancy rate to TAI as treatment with EB 24 h after P4 removal. The use of EC requires one less handling which is highly important in facilitating practical adoption of TAI in assisted breeding and genetic improvement in buffalo.

Exogenous and endogenous factors in seasonality of reproduction in buffalo: A review

Seasonal breeding in buffalo is influenced by exogenous (photoperiod, climate, nutrition, management) and endogenous (hormones, genotype) factors. Buffalo are negatively photoperiodic and show a natural increase in fertility during decreasing day length. The hormone melatonin is produced by the pineal gland and has a fundamental role in photoperiodic time measurement within the brain. This drives annual cycles of gonadotropin secretion and gonadal function in buffaloes. Some melatonin is released into the systemic circulation and, together with peripherally produced melatonin, acts at somatic tissues. In the ovaries and testes of buffalo, melatonin acts as an antioxidant and scavenges oxygen free radicals to reduce both oxidative stress and apoptosis. This has beneficial effects on gametogenesis and steroidogenesis. Female buffalo treated with melatonin show an improved response to estrus synchronization protocols in out-of-season breeding. Melatonin acts through melatonin receptors MT₁ and MT₂ and the gene for MT₁ (MTNR1A) is polymorphic in buffaloes. Single nucleotide polymorphisms (SNPs) in gene MTNR1A have been associated with fertility in female buffalo. The knowledge and tools are available to lift the reproductive performance of buffalo. This is highly important as the global demand for nutritious buffalo food products has undergone a sharp rise, and continues to grow. Buffalo can make an important contribution to affordable, nutritious animal protein. This will help address global nutritional security.

Adhesion molecules in gamete transport, fertilization, early embryonic development, and implantation-role in establishing a pregnancy in cattle: A review

Cell-cell adhesion molecules have critically important roles in the early events of reproduction including gamete transport, sperm-oocyte interaction, embryonic development, and implantation. Major adhesion molecules involved in reproduction include cadherins, integrins, and disintegrin and metalloprotease domain-containing (ADAM) proteins. ADAMs on the surface of sperm adhere to integrins on the oocyte in the initial stages of sperm-oocyte interaction and fusion. Cadherins act in early embryos to organize the inner cell mass and trophectoderm. The trophoblast and uterine endometrial epithelium variously express cadherins, integrins, trophinin, and selectin, which achieve apposition and attachment between the elongating conceptus and uterine epithelium before implantation. An overview of the major cell-cell adhesion molecules is presented and this is followed by examples of how adhesion molecules help shape early reproductive events. The argument is made that a deeper understanding of adhesion molecules and reproduction will inform new strategies that improve embryo survival and increase the efficiency of natural mating and assisted breeding in cattle.

Short communication: Space allocation in intensive Mediterranean buffalo production influences the profile of functional biomolecules in milk and dairy products

The aim of the present study was to determine if space allocation influenced the concentration of biomolecules in buffalo milk and dairy products. Intensively housed buffaloes (n = 96) were randomly assigned to 2 groups according to days in milk, parity, and milk yield: group S10 had a space allocation of 10 m² per buffalo and group S15 had a space allocation of 15 m² per buffalo. Individual milk yield was recorded daily. Twice a month, a bulk milk sample was collected for each group, as well as whey, ricotta, and mozzarella cheese, to assess cheese yield and to conduct HPLC-electrospray ionization-tandem mass spectrometry, milk antioxidant activity, and cell viability analyses. We tested milk extracts from the 2 groups in vitro to evaluate their efficacy in counteracting endothelial oxidative damage induced by high glucose. We evaluated reproductive function in 28 buffaloes from each group using the Ovsynch-timed artificial insemination program. We observed no differences in milk quantity or quality in terms of fat, protein, or lactose, and reproductive function did not differ between the 2 groups. Compared with group S10, group S15 had higher concentrations of carnitine (56.7 ± 1.1 vs. 39.8 ± 0.7 mg/L in milk and 40.9 ± 0.8 vs. 31.7 ± 0.7 mg/L in whey), acetyl-l-carnitine (51.9 ± 0.3 vs. 39.7 ± 0.7 mg/L in milk and 41.1 ± 1.7 vs. 28.7 ± 2.6 mg/L in whey), propionyl-l-carnitine (34.8 ± 1.0 vs. 21.0 ± 0.9 mg/L in milk and 26.9 ± 0.8 vs. 17.6 ± 1.2 mg/L in whey), glycine betaine (23.1 ± 1.9 vs. 13.5 ± 1.6 mg/L in milk and 10.7 ± 0.4 vs. 7.9 ± 0.5 mg/L in whey), and δ-valerobetaine (24.2 ± 0.5 vs. 16.7 ± 0.5 mg/L in milk and 22.0 ± 0.9 vs. 15.5 ± 0.7 mg/L in whey). Group S15 also had higher total antioxidant activity than group S10 (56.7 ± 1.9 vs. 46.4 ± 1.13 mM Trolox equivalents). Co-incubation of high-glucose-treated endothelial cells with milk extracts from group S15 improved cell viability compared with cells treated with high glucose only; it also reduced intracellular lipid peroxidation (144.3 ± 0.4 vs. 177.5 ± 1.9%), reactive oxygen species (141.3 ± 0.9 vs. 189.3 ± 4.7 optical density units), and cytokine release (tumor necrosis factor-α, IL-1β, IL-6). Greater space allocation was associated with higher levels of biomolecules in buffalo milk. This could have been the result of improved welfare in buffaloes that were allocated more space.

Ovarian follicular growth suppression by long-term treatment with a GnRH agonist and impact on small follicle number, oocyte yield, and in vitro embryo production in Zebu beef cows

The aim of the present study was to evaluate small follicle number, oocyte yield, and in vitro embryo production (IVEP) in Zebu beef cows treated long term with a GnRH agonist to suppress ovarian follicular growth. Nelore (Bos indicus) cows (n = 20) showing regular estrous cycles were randomly assigned to one of two groups: control (n = 10, placebo ear implant without a GnRH agonist); GnRH agonist (n = 10, GnRH agonist ear implant containing 9.4-mg deslorelin). All cows underwent an ovum pick-up (OPU) session 14 days (Day 14) before the start of treatments (Day 0) followed by seven OPU-IVEP procedures at 30-day intervals (Days 0, 30, 60, 90, 120, 150, and 180). Semen from a single batch of a previously tested bull was used for all the IVEP. Cows treated with agonist reported a decrease over time in the proportion of animals with a (CL; P ≤ 0.05) and large follicles (>10 mm, P ≤ 0.05). These cows had a lesser number of medium + large follicles (>5 mm; 1.74 ± 0.5 vs. 4.13 ± 0.5; P ≤ 0.05), greater number of small follicles (2-5 mm; 44.3 ± 2.8 vs. 30.8 ± 1.8; P ≤ 0.05), greater yield of cumulus-oocyte complexes (COCs; 21.0 ± 2.3 vs. 15.6 ± 1.9; P ≤ 0.05), greater proportion of COCs cultured (79.2 vs. 73.9%; P ≤ 0.05), COCs cleaved (10.6 ± 1.5 vs. 6.8 ± 1.1, P ≤ 0.05), and cleaved rate (52.8 vs. 44.3%; P ≤ 0.05) compared with control cows. The number (3.4 ± 0.7 vs. 3.0 ± 0.6; P > 0.05) and proportion (16.5 vs. 19.1%; P > 0.05) of blastocysts produced were similar between agonist and control cows, respectively. The study has shown that Zebu beef cows treated long term with a GnRH agonist had follicular growth restricted to small follicles. This did not compromise the ability of oocytes to undergo IVF and embryonic development.

Design, synthesis and evaluation of a gonadotropin releasing hormone-based subunit vaccine in rams (Ovis aries)

Immunocastration using gonadotropin-releasing hormone (GnRH)-based vaccines has been investigated in rams to reduce aggressive and sexual behaviour and to control meat quality. Despite considerable efforts, a practical GnRH vaccine has yet to be developed for rams. In the present study, a A GnRH-lipopeptide vaccine (GnRH-LP) including two copies of GnRH, 2-amino-d,l-hexadecanoic acid (C16), and a unique T helper epitope, was examined in rams. Rams received a primary and secondary vaccination of GnRH-LP without additional adjuvant (Group 1) or with the adjuvant AdjuVac™ (Group 2). In both Group 1 and 2 anti-GnRH antibody titres increased after secondary vaccination, however, the antibody titres were higher (p<0.01) for rams in Group 2. The latter rams showed a marked decrease in testicular size. The marked and sustained reduction in testicular size in rams treated with GnRH-LP+AdjuVac™ provides the basis for an effective immunocastration vaccine in rams.

Interrelationships of nutrition, metabolic hormones and resumption of ovulation in multiparous suckled beef cows on subtropical pastures

The effect of nutrition before and after calving on metabolic status and the resumption of ovulation postpartum was examined in multiparous sucked beef cows on subtropical pastures. At 6-7 months of gestation, Droughtmaster cows were randomly assigned on body weight (BW) and stage of gestation to two groups that received either standard subtropical pasture (SP, n = 7, 543 ± 12 kg BW) or improved pasture (IP, n = 7, 564 ± 12 kg BW). The two nutritional treatments were maintained after calving. Starting at 1 week after calving, cows were monitored for BW and body condition score (BCS, biweekly) and for circulating concentrations of insulin, glucose, IGF-1, GH and leptin (weekly). Ovarian follicular status was monitored weekly by trans-rectal ultrasonography. Fecal samples were obtained at 3-week intervals to ascertain percentage crude protein (%CP) and dry matter digestibility (DMD) of pastures. Crude protein and DMD were greater (P < 0.05) for cows on IP during the first 9 weeks after calving after which there were no differences between nutritional treatments. Cows on IP were heavier (P < 0.05) and had a greater (P < 0.01) BCS than cows on SP at 1 week after calving (585 ± 9 kg and 3.7 ± 0.2 BCS and 528 ± 21 kg and 2.3 ± 0.2 BCS, respectively). Cows on SP showed a gradual increase in BW and there were no differences in BW after approximately 7 weeks postpartum whilst BCS remained less for cows on SP. Plasma concentrations of insulin, glucose, IGF-1 and leptin were all greater (P < 0.01) for cows on IP compared with cows on SP, whilst GH did not differ. The diameter of the largest follicle did not differ between cows on IP and SP throughout the postpartum period. However, 7 of 7 cows on IP resumed ovulations between 12 and 15 weeks postpartum whilst only 1 of 7 cows on SP had resumed ovulation during the study. It is concluded from the findings that exposure of cows to IP and SP before and after calving resulted in two groups of cows with different metabolic homeostasis and that the greater circulating concentrations of insulin, glucose, IGF-1 and leptin promoted the earlier resumption of ovulation for cows on IP.

Lipid content, active mitochondria and brilliant cresyl blue staining in bovine oocytes

Bovine oocytes that stain with brilliant cresyl blue (BCB) have a relatively higher developmental competence. The aim of the present study was to investigate the relationships among BCB staining, lipid content, and active mitochondria. Bovine oocytes (N = 133) with at least three layers of cumulus cells were segregated as BCB retained (BCB+) or metabolized (BCB-) and then stained for active mitochondria (Mitotracker Red) and lipid (Bodipy), with analysis by confocal microscopy. The BCB+ oocytes (N = 45) contained approximately 26% more cytoplasmic lipid than BCB- oocytes (N = 26-27; P < 0.05). Staining for active mitochondria did not differ between the groups. In BCB- oocytes but not BCB+ oocytes, lipid content correlated with active mitochondrial staining (r = 0.48; P < 0.05). Diameter correlated with lipid content for BCB+ oocytes (r = 0.46; P < 0.05), but not for BCB- oocytes (r = 0.16; P > 0.05). Irrespective of BCB staining, both lipid and active mitochondrial content correlated with diameter. In conclusion, the higher lipid content of BCB+ bovine oocytes might provide a cellular and functional basis for their greater developmental competence.

Influence of season on corpus luteum structure and function and AI outcome in the Italian Mediterranean buffalo (Bubalus bubalis)

The aim was to ascertain whether relationships between corpus luteum (CL) vascularization, CL function, and pregnancy outcome in AI in buffaloes were consistent across the breeding season and transition period to the nonbreeding season in a Mediterranean environment. Stage of the estrous cycle in Italian Mediterranean buffaloes was synchronized using the Ovsynch with timed AI program and buffaloes were mated by AI in both the breeding season (N = 131) and transition period (N = 125). Detailed investigation of CL structure and function was undertaken in 39 buffaloes at each of the respective times using realtime B-mode/color-Doppler ultrasonography on Days 10 and 20 after AI. Progesterone (P4) concentrations were determined by RIA in all buffaloes. Pregnancy rate on Day 45 after AI was greater (P < 0.05) during the breeding season (58.0%) than the transitional period (45.6%) and this was primarily the result of a lower (P < 0.05) late embryonic mortality during the breeding season (7.3%) compared with the transition period (23%). Circulating concentrations of P4 on Days 10 and 20 after AI were greater (P < 0.01) during the breeding season (4.6 ± 0.3 and 3.4 ± 0.2, respectively) than during the transition period (1.6 ± 0.12 and 1.8 ± 0.2, respectively), and this was independent of reproductive status as there was no interaction between pregnancy and season. Corpus luteum time average medium velocity at Day 10 after AI was greater (P < 0.01) during the breeding season (19.3 ± 1.5) than in the transitional period (8.3 ± 0.7). There were positive correlations in pregnant buffaloes between CL time average medium velocity and P4 concentrations on Day 10 (r = 0.722; P < 0.01) and Day 20 (r = 0.446; P < 0.01) after AI. The findings were interpreted to indicate that relationships between CL vascularization, CL function, and pregnancy outcome in AI in buffaloes are consistent across the breeding season and transition period to the nonbreeding season. The distinction between the breeding season and the transition period is the relatively low proportion of buffaloes that have CL function and P4 concentrations required to establish a pregnancy during the transition period, which is manifested in a greater incidence of embryonic mortality.

Molecular genetic approaches for identifying the basis of variation in resistance to tick infestation in cattle

In recent years there has been renewed interest in the adaptation of cattle to challenging environments, largely driven by advances in genomic methods. The current interest in tick resistance is understandable given the major production and welfare implications of tick infestation in tropical and subtropical zones where around 70% of beef cattle are located. Heritability for tick burden in cattle has been shown to range about 0.30, which is sufficient to result in the success of some programs of selection for tick resistance in cattle. Gene-expression studies strongly indicate that both immune and non-immune mechanisms are associated with tick resistance in cattle. Recent quantitative-trait mapping studies have identified chromosome segments and single nucleotide polymorphisms associated with tick burden, but no causal variant has been identified so far. Most of the genetic markers identified for tick burden explain a relatively small proportion of the variance, which is typical of markers for quantitative traits. This leads to the conclusion that panels of multiple markers for tick resistance rather than a single marker will most likely be developed, possibly involving specific panels for zebu or taurine breeds, which could be used for future selection and breeding programs in cattle.

Growth, metabolic status and ovarian function in buffalo (Bubalus bubalis) heifers fed a low energy or high energy diet

The aim was to establish the capacity of buffalo heifers to adapt their metabolic requirements to a low energy diet. Murrah buffalo (Bubalus bubalis) heifers undergoing regular estrous cycles were randomly assigned by age, live weight (LW) and body condition score (BCS) to a high energy group (HE, 5.8 milk forage units (MFU)/day, n=6) or low energy group (LE, 3.6 MFU/day, n=6). Circulating concentrations of metabolic substrates, metabolic hormones and reproductive hormones were determined weekly for 19 weeks. Ovarian follicular characteristics and oocyte parameters were also ascertained weekly. Heifers fed the LE diet had a better dry matter conversion than heifers fed the HE diet and the calculated daily energy provision was negative for heifers fed the LE diet (-0.248 MFU) and positive for heifers fed the HE diet (5.4 MFU). Heifers fed the HE diet had an increase in 50 kg LW over the duration of the study whereas LW remained constant for heifers fed the LE diet. The BCS of heifers fed the HE diet (4.2) was greater (P<0.05) than the BCS for heifers fed the LE diet (3.4). Heifers fed the HE diet had greater (P<0.05) circulating concentrations of metabolic substrates (glucose, total cholesterol and HDL cholesterol) and metabolic hormones (insulin, glucagon, leptin and T3) compared with heifers fed the LE diet. There were no significant differences in circulating reproductive hormones between the two groups of heifers. Ovarian follicular characteristics were similar for the two groups of heifers while heifers fed the LE diet tended to have oocytes of reduced quality compared with heifers fed the HE diet. The most notable finding was that heifers fed the LE diet had a negative calculated daily energy provision but were able to maintain LW and reproductive activity. It was concluded that buffalo heifers may potentially have the capacity to undergo metabolic adjustment and reduce their energy requirements when dietary energy is limiting. This adaptive capacity would explain why buffaloes remain productive in environments that are limiting to other ruminants.

Is a delayed treatment with GnRH, HCG or progesterone beneficial for reducing embryonic mortality in buffaloes?

The aims of this study were to verify the efficacy of delayed hormonal treatments performed on day 25 post-insemination on pregnancy rate at 45 and 70 days in buffalo. The trial was performed on 385 buffaloes synchronized by the Ovsynch/TAI protocol and submitted to artificial insemination (AI). Twenty-five days after AI, pregnant animals were assigned to four treatments: (1) GnRH agonist (n = 52), 12 microg of buserelin acetate; (2) hCG (n = 51), 1500 IU of human chorionic gonadotrophin; (3) Progesterone (n = 47), 341 mg of P4 intramuscular (im) every 4 days for three times; (4) Control (n = 54), treatment with physiological saline (0.9% NaCl). Milk samples were collected on days 10, 20 and 25 after AI in all buffaloes to determine progesterone concentration in whey by radioimmunoassay method. Statistical analysis was performed by anova. Pregnancy rate on day 25 after AI was 52.9%, but declined to 41.8% by day 45, indicating an embryonic mortality (EM) of 21%. If only control group is considered, the incidence of EM was 38.9%. Pregnant buffaloes had higher (p < 0.01) progesterone concentrations on day 20 and 25 after AI than both non-pregnant buffaloes and buffaloes that showed EM. The treatments on day 25 increased (p < 0.01) pregnancy rate, although in buffaloes with a low whey progesterone concentration on day 20 and 25 after AI (n = 22); all treatments were ineffective to reduce EM.

Delayed treatment with GnRH agonist, hCG and progesterone and reduced embryonic mortality in buffaloes

The present study examined the effect of delayed treatment with tropic hormones and progesterone (P4) on embryonic mortality in buffaloes. Buffaloes with a conceptus on Day 25 after AI were assigned to the following treatments: Control (n=41), i.m. physiological saline; GnRH agonist (n=36), i.m. 12 microg buserelin acetate; hCG (n=33), i.m. 1500 IU hCG; P4 (n=38), i.m. 341 mg P4 every 4 days on three occasions. Control buffaloes had an embryonic mortality of 41.4% (17/41) between Days 25 and 45, and this was reduced (P<0.01) by treatment with GnRH agonist (11.1%, 4/36), hCG (9.0%, 3/33) and P4 (13.1%, 5/38). On Day 45, buffaloes treated with hCG and which ovulated had greater (P<0.05) concentrations of P(4) in whey (453 +/- 41 pg/ml) than buffaloes in the same treatment that did not ovulate (297 +/- 32 pg/ml). A similar but non-significant trend was observed for buffaloes treated with GnRH agonist. It was concluded from the findings that the treatment of buffaloes on Day 25 after AI with tropic hormones or P4 is beneficial to processes associated with embryonic implantation.

Expression of FGF2 and TGFalpha and testis morphology during testicular hypertrophy subsequent to hemicastration in the neonatal boar

The objective was to ascertain fibroblast growth factor-2 (FGF2), epidermal growth factor (EGF), and transforming growth factor-alpha (TGFalpha) mRNA expression and testis morphology during accelerated testicular growth after hemicastration in the neonatal boar. On Day 10 after birth (Day 0), boars were assigned to control (n = 28), no treatment; hemicastrated (n = 28), left testis removed. The right testis in both groups (n = 7) was removed on Days 5, 10, 15, and 20. Expression of mRNA for FGF2, EGF, and TGFalpha was determined by qRT-PCR using TaqMan. Testicular morphology was determined on Day 15. On Day 10, hemicastrated boars had a greater (P = 0.01) testis weight (6.2 +/- 0.8 g; mean +/- SEM) than controls (4.3 +/- 0.4 g) and on Day 15 testis weight in hemicastrated boars (8.8 +/- 0.8 g) was twice (P < 0.01) that of control boars (4.2 +/- 0.3 g). Seminiferous tubule volume was approximately doubled in hemicastrated boars (P < 0.01) and was associated with an increase (P < 0.01) in Sertoli cell number. Interstitial compartment volume was greater (P < 0.01) in hemicastrated boars. Leydig cell numbers were similar (P = 0.14) but volume was greater (P < 0.01) for hemicastrates. There were no differences (P > 0.05) between control and hemicastrated boars in TGFalpha or FGF2 expression on Day 5 or Day 10, and EGF was not detected. It was concluded that upregulation of TGFalpha or FGF2 expression is not a pre-requisite for enhanced testicular growth and increased Sertoli cell proliferation that occurs subsequent to hemicastration in the neonatal boar.

Testicular development of Zebu bulls after chronic treatment with a gonadotropin-releasing hormone agonist

The objective was to compare testis characteristics of Zebu bulls treated with the GnRH agonist, deslorelin, at different times and for different durations during their development. An additional objective was to determine the usefulness of a stain for the transcription factor GATA-binding protein 4 (GATA-4) as a specific marker for Sertoli cell nuclei in cattle. Bulls (54) were allocated to nine groups (n = 6) and received s.c. deslorelin implants as follows: G1 = from birth to 3 mo of age; G2 = from 3 to 6 mo; G3 = from 6 to 9 mo; G4 = from 9 to 12 mo; G5 = from birth to 15 mo; G6 = from 3 to 15 mo; G7 = from 6 to 15 mo; G8 = from 12 to 15 mo; and G9 (control) = no implant. Bulls were castrated at 19 mo of age. Paraffin sections (10 microm) were subjected to quantitative morphometry and GATA-4 immunohistochemistry. At castration, all bulls in the control group (6/6) had attained puberty (scrotal circumference > or = 28 cm), whereas a smaller proportion (P < 0.05) had reached puberty in G2 (2/5) and G6 (1/6). Bulls in G2 and G6 also had a lesser (P < 0.05) testis weight compared with the control group. Total volume of seminiferous epithelium and total daily sperm production in G2 and G6 were only half that observed in the control group. Spermatids were observed in less than 50% of seminiferous tubules in G2, G6, and G7 compared with 82% in the control group (P < 0.05). Staining for GATA-4 was specific for and abundant in the Sertoli cell nucleus in both pre- and postpubertal bulls, and no other cell nucleus inside the seminiferous tubule was positive for GATA-4. Total number of Sertoli cells was not affected by treatment (P = 0.45), but nuclear volume was smaller in G2 and G6 (P < 0.05) compared with the control group. In conclusion, treatment of Zebu bulls with deslorelin had no apparent beneficial effect on testis development and delayed puberty when treatment was initiated at 3 mo of age. Staining for GATA-4 was a useful method for identifying and quantifying Sertoli cell nuclei in both pre- and postpubertal bulls.

Pituitary expression of LHbeta- and FSHbeta-subunit mRNA, cellular distribution of LHbeta-subunit mRNA and LH and FSH synthesis during and after treatment with a gonadotrophin-releasing hormone agonist in heifers

The aim was to examine transcriptional and post-transcriptional regulation of LH and FSH biosynthesis. Female cattle were allocated to three groups: (i) Group 1, control (n = 6), synchronized to be at around Day 11 of the oestrous cycle on Day 31; (ii) Group 2 (n = 6), treated with gonadotrophin-releasing hormone (GnRH) agonist (deslorelin) for 31 days; and (iii) Group 3 (n = 6), treated with deslorelin for 28 days. All animals were slaughtered on Day 31. For animals in Group 2, pituitary content of LHbeta-subunit mRNA was suppressed 60% (P < 0.001) and LH 95% (P < 0.001), whereas FSHbeta-subunit mRNA was suppressed 25% (P > 0.05) and FSH 90% (P < 0.001). Three days after treatment with deslorelin (Group 3) LHbeta-subunit mRNA and LH remained suppressed (50% and 95%, respectively; P < 0.001). At the same time, FSHbeta-subunit mRNA did not differ from controls (P > 0.05) whereas FSH remained reduced by 80% (P < 0.001). The ratio of LHbeta-subunit mRNA present in the nucleus versus cytoplasm of gonadotroph cells was reduced (P < 0.05) in heifers during treatment with deslorelin (0.59 +/- 0.05) compared with the ratio in control heifers (1.31 +/- 0.22) and heifers 3 days after discontinuation of treatment (1.01 +/- 0.05). The findings indicated that treatment with GnRH agonist can suppress LHbeta-subunit mRNA expression without any significant effect on FSHbeta-subunit mRNA. As LH and FSH contents were suppressed to a greater degree than their beta-subunit mRNAs, it would appear that treatment with a GnRH agonist might influence gonadotrophin biosynthesis by a post-transcriptional mechanism(s). For LHbeta-subunit mRNA, this would appear not to be reduced export of message from the nucleus.

Biology of sperm chromatin structure and relationship to male fertility and embryonic survival

Embryonic mortality in mammals is typically thought to result from 'female factor' infertility. There is growing evidence, however, that the status of sperm chromatin (DNA) at the time of fertilisation can also influence embryonic survival. During the final stages of spermatogenesis (spermiogenesis) a number of unique biochemical, morphological and physiological processes take place that are associated with marked changes in the structure of sperm chromatin. In early stages of spermatogenesis, sperm DNA is associated with histone nucleoproteins and structured into classical nucleosome core particles similar to other somatic cells. As spermiogenesis proceeds, the histone nucleoproteins are replaced by transition proteins which are subsequently replaced by protamines. At the completion of spermiogenesis the chromatin of mature sperm has a toroidal structure that is tightly compacted and resistant to denaturation. The compaction is necessary to protect sperm chromatin during transit through the epididymis and female reproductive tract. Disruption to chromatin remodelling during spermiogenesis results in chromatin that is susceptible to denaturation. Inappropriate chromatin structure has been shown in a number of mammalian species to be related to male infertility, and specifically the failure of embryonic development. A range of techniques are available to assess chromatin status in sperm but arguably the most informative is the sperm chromatin structure assay (SCSA). The SCSA is a flow cytometric assay that uses the metachromatic properties of acridine orange to measure the susceptibility of sperm chromatin to acid-induced denaturation. A relationship has been demonstrated, primarily in men, between the SCSA outcome and the probability of continued embryonic development and the establishment of pregnancy after fertilisation. The contribution of sperm chromatin instability to reproductive wastage in both natural mating and assisted reproduction warrants further investigation as it may prove valuable as a means of decreasing the incidence of embryonic mortality. In this regard, it is possible that 'male factor' infertility may emerge as an even more important component in embryonic development.

Corpus luteum function and embryonic mortality in buffaloes treated with a GnRH agonist, hCG and progesterone

The effect of treatment with a GnRH agonist, hCG or progesterone (P(4)) on corpus luteum function and embryonic mortality was investigated in buffaloes inseminated during mid-winter. Italian Mediterranean buffaloes (n=309) were synchronized using the Ovsynch with timed-AI program and mated by AI at 16 h (Day 0) and 40 h after the second injection of GnRH. On Day 5, buffaloes were randomly assigned to four groups: Control (no treatment, n=69), GnRH agonist (buserelin acetate, 12.6 microg, n=73), hCG (1500 IU, n=75) and P(4) (PRID without E(2) for 10 days, n=77). Progesterone (pg/ml) was determined in milk whey on Days 5, 10, 15 and 20 and pregnancy diagnosis was undertaken on Day 26 by ultrasound and Day 40 by rectal palpation. Treatment with buserelin and hCG increased (p<0.05) P(4) on Day 15 compared with controls (456+/-27, 451+/-24 and 346+/-28 pg/ml, respectively). Buffaloes treated with a PRID had intermediate P(4) concentrations (380+/-23 pg/ml). Embryonic mortality between Days 26 and 40 (22.9%) and pregnancies at Day 40 (48.9%) did not differ between treatments. A higher (p<0.01) P(4) concentration was found on Day 20 in pregnant animals compared with non-pregnant and embryonic mortality buffaloes, which did not differ. In summary, buserelin and hCG increased P(4) concentrations on Day 15 but this was not associated with a reduced incidence of embryonic mortality in buffaloes during mid-winter.

Comparative response of rams and bulls to long-term treatment with gonadotropin-releasing hormone analogs

The objective was to compare the relative response between rams and bulls in characteristics of LH, FSH and testosterone (T) secretion, during and after long-term treatment with GnRH analogs. Animals were treated with GnRH agonist, GnRH antagonist, or vehicle (Control) for 28 days. Serial blood samples were collected on day 21 of treatment, and at several intervals after treatment. Injections of natural sequence GnRH were used to evaluate the capacity of the pituitary to release gonadotropins during and after treatment. Treatment with GnRH agonist increased basal LH and T concentrations in both rams and bulls, with a greater relative increase in bulls. Endogenous LH pulses and LH release after administration of GnRH were suppressed during treatment with GnRH agonist. Treatment with GnRH antagonist decreased mean hormone concentrations, LH and T pulse frequency, and the release of LH and T after exogenous GnRH, with greater relative effects in bulls. Rams previously treated with antagonist had a greater release of LH after administration of GnRH compared with control rams, while rams previously treated with agonist showed a reduced LH response. Bulls previously treated with agonist had reduced FSH concentrations and LH pulse amplitudes compared with control bulls while bulls previously treated with antagonist had greater T concentrations and pulse frequency. The present study was the first direct comparison between domestic species of the response in males to treatment with GnRH analogs. The findings demonstrated that differences do occur between rams and bulls in LH, FSH and testosterone secretion during and after treatment. Also, the consequences of treatment with either GnRH analog can persist for a considerable time after discontinuation of treatment.

Use of a GnRH Agonist and hCG to Obtain an Index of Testosterone Secretory Capacity in the Koala (Phascolarctos cinereus)

Testosterone secretion in mammals typically occurs in random pulses such that a single blood sample provides limited information on reproductive endocrine status. However, it has been shown in several species that an index of the prevailing testosterone biosynthetic capacity of the testes can be obtained by measuring the increase in circulating testosterone after injection of a GnRH agonist or human chorionic gonadotrophin (hCG). Hence, the aims of the present study were to examine fluctuations in testosterone secretion in the koala (n = 6) over a 24-hour period and then characterise testosterone secretion after injection of the GnRH agonist buserelin (4 micro g) or hCG (1000 IU). The latter was used to establish an index of the prevailing testosterone biosynthetic capacity of the koala testis. Individual koalas showed major changes in blood testosterone concentrations over 24 hours, but there was no apparent diurnal pattern of testosterone secretion (P > .05). Injection of buserelin and hCG resulted in an increase (P < .05) in blood testosterone concentration. After injection of exogenous hormone, near maximal concentrations of testosterone occurred at around 60 minutes. There was a tendency for plasma testosterone to decline after 90 minutes with buserelin, but concentrations remained close to the upper limit for 240 minutes with hCG. There were strong positive correlations between the average testosterone concentration over 24 hours and the maximum observed testosterone concentration after stimulation with GnRH and hCG (GnRH, r = .772; P = .07 and hCG, r = 1.0; P < .01). The findings in the present study confirmed that individual male koalas can show large fluctuations in blood testosterone concentrations over time and that a GnRH agonist and hCG can be used in the koala to obtain an index of the prevailing steroidogenic capacity of the testes.

Relationship of body condition score and blood urea and ammonia to pregnancy in Italian Mediterranean buffaloes

The relationship of body condition score (BCS) and blood urea and ammonia to pregnancy outcome was examined in Italian Mediterranean Buffalo cows mated by AI. The study was conducted on 150 buffaloes at 145 +/- 83 days in milk that were fed a diet comprising 14.8% crude protein, 0.9 milk forage units.kg-1 dry matter and a non-structural carbohydrate/crude protein ratio of 2.14. The stage of the oestrous cycle was synchronised by the Ovsynch-TAI programme and blood urea and ammonia levels were assessed on the day of AI. Energy corrected milk (ECM) production and BCS were recorded bi-weekly. The pregnancy risk was 46.7% and was slightly lower in buffaloes with BCS < 6.0 and BCS > 7.5. There were no significant differences in ECM, urea and ammonia between pregnant and non-pregnant buffaloes. However, pregnancy outcome was higher (P = 0.02) in buffaloes with blood urea < 6.83 mmol.L-1. The likelihood of pregnancy for buffaloes with low urea blood level was 2.6 greater than for high urea level and exposure to a high urea level lowered the probability of pregnancy by about 0.25. The findings indicate that buffaloes are similar to cattle and increased blood levels of urea are associated with reduced fertility when animals are mated by AI.

Remodeling of extracellular matrix at ovulation of the bovine ovarian follicle

Using immunohistochemistry and RNA analyses we examined the fate of components of a newly identified matrix that develops between granulosa cells (focimatrix, abbreviated from focal intraepithelial matrix) and of the follicular basal lamina in ovulating bovine ovarian follicles. Pre- and postovulatory follicles were generated by treatment with estradiol (Day 1), progesterone (Days 1-10), and prostaglandin analogue (Day 9) with either no further treatment (Group 1, n = 6) and or with 25 mg porcine LH (Day 11, Group 2, n = 8 or Day 10, Group 3, n = 8) and ovariectomy on Day 12 (12-14 hr post LH in Group 2, 38-40.5 hr in Group 3). In the time frame examined no loss of follicular basal lamina laminin chains beta2 and gamma1 or nidogen 1 was observed. In the follicular basal lamina collagen type IV alpha1 and perlecan were present prior to ovulation; after ovulation collagen type IV alpha1 was discontinuously distributed and perlecan was absent. Versican in the theca interna adjacent to the follicular basal lamina in preovulatory follicles was not observed post ovulation, however, the granulosa cells then showed strong cytoplasmic staining for versican. Expression of versican isoforms V0, V1, and V3 was detected at all stages. Focimatrix was observed in preovulatory follicles. It contained collagen type IV alpha1, laminins beta2 and gamma1, nidogen 1 and perlecan and underwent changes in composition similar to that of the follicular basal lamina. In conclusion focimatrix and the follicular basal lamina are degraded at ovulation. Individual components are lost at different times.

Testosterone secretion and pharmacological spermatozoal recovery in the cane toad (Bufo marinus)

The cane toad (Bufo marinus) was used as a model to study male anuran reproductive endocrinology and to develop a protocol for non-invasive sperm recovery. Circulating testosterone concentrations in 6-hourly samples did not vary significantly (P < 0.05) over a 24 h period although there was a tendency (P = 0.06) for testosterone to be elevated at 19:00 h relative to other times of the day, which may be related to the nocturnal activity pattern of this species. Testosterone secretion after intraperitoneal (IP) injection of either a GnRH agonist (5 microg IP) or hCG (1000 IU) was also examined. While the GnRH agonist did not produce a significant increase above basal plasma testosterone (0.29, 95% C.I. of 0.05-1.10 ng/ml), injection of hCG resulted in an increase (P < 0.01) of plasma testosterone with peak concentrations at approximately 120 min (4.17, 95% C.I. of 2.69-7.44 ng/ml) after injection. Non-invasive pharmaceutical sperm recovery was attempted following IP injection of graded doses of GnRH agonist, hCG or FSH. Urine was collected at 3, 6 and 12 h after treatment to assess sperm quality and quantity. The optimal protocol for sperm recovery in cane toads was injection of either 1000 or 2000 IU hCG; there was no significant difference in the quality of the spermic urine samples obtained using either dose of hCG or with respect to collection time. The findings indicated that hCG can be used to assess testicular steroidogenic status and also to induce sperm recovery in the cane toad. The hCG protocols developed in this study will have application in studies on the reproductive biology of rare and endangered male anurans.

Embryonic mortality in buffaloes synchronized and mated by AI during the seasonal decline in reproductive function

The aim was to determine the factors that contribute to embryonic mortality in buffaloes mated by AI during a period of increasing day length which corresponds to a natural decline in reproductive activity. Italian Mediterranean buffalo cows (n=243) showing regular estrous cycles were synchronized using the Ovsynch-TAI program and mated by AI at 16 and 40 h after the second injection of GnRH. Blood samples were collected on Days 10 and 20 after the first AI and assayed for progesterone (P4). Pregnancy diagnosis was undertaken on Days 26 and 40 after the first AI using rectal ultrasonography. Buffaloes with a conceptus on Day 26 but not on Day 40 were judged to have undergone embryonic mortality and for these animals uterine fluid was recovered by flushing and analysed for common infectious agents. Estrus synchronization was achieved in 86% of buffaloes and the pregnancy rate on Day 40 was 34%. Embryonic mortality between Days 26 and 40 occurred in 45% of buffaloes and was associated with the presence of significant infectious agents in only 10 buffaloes (8%). Concentrations of P4 on Day 10 after AI were higher (P<0.05) in buffaloes that established a pregnancy than in buffaloes that showed embryonic mortality that was not associated with infectious agents. Similarly, on Day 20 after AI P4 concentrations were higher (P<0.01) in pregnant buffaloes compared with non-pregnant buffaloes and buffaloes that had embryonic mortality. It is concluded that a reduced capacity for P4 secretion can explain around 50% of embryonic mortalities in buffaloes synchronised and mated by AI during a period of low reproductive activity and that other as yet unidentified factors also have a significant effect on embryonic survival.

Trial introduction of the Willis dropped ovary technique for spaying cattle in northern Australia

OBJECTIVE

To compare the Willis dropped ovary technique with traditional spaying methods in extensive beef cattle herds in northern Australia.

PROCEDURE

Three field trials were conducted simultaneously at different sites in northern Australia in 1996-97. Brahman and Brahman-Shorthorn cross heifers (n = 219, 2 years, 250 to 378 kg) and cows (n = 211, 3 to 16 years, 256 to 540 kg) were allocated by stratified randomisation to three treatments: spaying using the Willis dropped ovary technique (WDOT); spaying using traditional paralumbar and vaginal methods; and unspayed. Following these procedures, these nonpregnant, nonlactating cattle were then exposed to bulls (4 per 100 females) under extensive rangeland conditions for 12 months during which time weight, body condition, pregnancy and ovarian function were monitored and compared.

RESULTS

Pregnancy rates varied from 60 to 90% for entire heifers and 80 to 100% for entire cows depending on site. The traditional spay methods were 100% successful in preventing pregnancy; the WDOT was 92 to 97% effective, depending on operator experience. The number of deaths was the same or higher in Willis spayed animals than other groups. Weight changes were similar in all groups at the three sites over the trial period. The time taken to spay using the WDOT was similar to or less than that required for the traditional methods. Uterine abnormalities were not observed in animals spayed with the WDOT, there were however 30 (12.4%) animals where excision of the ovary was incomplete; the still-attached ovarian remnant presumably accounting for the three pregnant animals in this group.

CONCLUSION

The WDOT suffers from requiring a high degree of skill in transrectal ovarian manipulation. There were more deaths and more pregnancies than with traditional spay methods. More experienced operators can be expected to achieve lower mortalities, better contraception and higher processing rates. Pregnancy will occur as a consequence of ovarian remnants unless care is taken to ensure removal of the entire ovary.

Ovarian follicular wave characteristics in alpacas

The objectives were to describe in detail ovarian follicular growth characteristics and to establish the interval between successive large follicles in unmated alpacas. The ovarian follicular status of 16 non-pregnant, non-lactating mature alpacas was recorded using ultrasound every second day for between 46 and 100 days. An inverse relationship was observed between the diameter of the largest follicle and the total number of follicles indicating that follicular growth in alpacas occurs in waves. There were 15/38 (39%) inter-wave intervals of 12 days and 12/38 (32%) intervals of 16 days. The maximum follicular diameter in each follicular wave was 8.8 +/- 0.3 mm (n=38). Inter-wave intervals of longer duration were associated with a larger maximum follicle diameter (P<0.001). However, the growth rate of dominant follicles was consistent over the first 10 days after emergence. They reached a diameter capable of ovulation by this time, regardless of subsequent inter-wave interval. The latter observation suggested that the optimal time of mating might be predicted in alpacas, provided that the emergence of ovarian follicular waves was controlled.

Influence of rumen protein degradability on productive and reproductive performance in buffalo cows

The present study aimed to ascertain the influence of crude protein (CP) digestibility in the rumen on the quantity and quality of milk production and reproductive performance, blood (BU) and milk (MU) urea, haematological profile and vaginal mucus urea, ammonia and potassium of buffalo cows. Lactating buffaloes (n = 84), 60 days in milk, were randomly subdivided into Group C (control, n = 42) and Group T (fed a diet supplemented with Aspergillus oryzae, n = 42). In three fistulated buffalo, the diet supplemented with Aspergillus oryzae showed a decrease (P < 0.01) in protein digestibility in the rumen (79.3 vs. 45.9%). No differences were registered in productive performance. Nine buffaloes not in oestrus during the dietary treatment (Groups T1 and C1), 30 days in milk, were used to study the haematological profile and to determine milk urea and ammonia in the vaginal mucus. The animals in Group T1 had higher ammonia values in the blood (P < 0.01) but not in the vaginal mucus than Group C1. A relationship was found between MU and BU. MU was influenced by CP intake and dry matter intake. No differences between the treatments were observed in reproductive performance and the conception rate and calving interval were 37.9% and 41.4% (90 trial-day) and 449 and 419 days respectively in Groups T and C. Reproductive performance was not influenced by high levels of BU nor by blood ammonia levels, although the latter were higher in the group fed the diet supplemented with Aspergillus oryzae.

Effect of chronic treatment with the gonadotrophin-releasing hormone agonist azagly-nafarelin on basal concentrations of LH in prepubertal bulls

Administration of GnRH agonist for an extended period inhibits pulsatile LH release but enhances testicular function of bulls. The mechanism whereby long-term administration of GnRH agonist enhances testosterone concentration in the blood of bulls has not been determined. The aim of this study was to determine whether chronic treatment with the GnRH agonist, azagly-nafarelin, increases blood concentrations of LH and FSH in prepubertal bulls. Two different doses of the GnRH agonist were administered via Alzet mini-osmotic pumps for 28 days. Blood samples were collected at 20 min intervals for 24 h at days 2, 13 and 25 of treatment. Agonist-treated groups had reduced testosterone pulse frequency (P < 0.05) and increased mean and basal concentrations of testosterone (P < 0.05) compared with untreated control bulls. Basal LH concentrations were higher in agonist-treated bulls during all three periods (P < 0.05) and overall (1 ng ml(-1) higher, compared with control bulls; P < 0.001). Frequency of LH pulses in the agonist-treated groups was reduced to less than one pulse in 24 h. Agonist-treated bulls tended to have (P < 0.10) or had (P < 0.05) a slight but significant increase in blood FSH concentration. In conclusion, the higher blood testosterone concentration in bulls after prolonged treatment with GnRH agonist may result, at least in part, from changes in the testes induced by enhanced basal concentration of LH.

Effects of mating behaviour and the ovarian follicular state of female alpacas on conception

OBJECTIVE

To determine relationships between mating behaviour, ovarian follicular state and successful conception in receptive female alpacas.

PROCEDURE

Seventy pen matings were observed at a commercial alpaca stud in south-western Victoria. The behaviours observed included time taken to assume sternal recumbency, mating duration, and evidence of nonreceptive behaviour such as spitting, kicking and vocalisation. Ovarian follicular state was determined by ultrasonography, which was complemented by measuring plasma concentrations of oestradiol and progesterone. Pregnancies were confirmed by transabdominal ultrasonography between days 45 and 80 after mating.

RESULTS

There were no significant differences between receptive females that conceived and those that failed to conceive in the time taken to adopt the copulation position of sternal recumbency, mating duration, or maximum follicle diameter. There was no significant relationship between time taken to assume sternal recumbency (log10) and maximum follicle diameter or plasma oestradiol (log10). However, there was a significant quadratic relationship between plasma oestradiol concentration (log10) and follicle diameter, and the probability of pregnancy increased as the plasma concentration of oestradiol (log10) at the time of mating increased. Females were sexually receptive most of the time in the absence of a corpus luteum, and regardless of size of the largest follicle or plasma concentration of oestradiol. Breed (Huacaya vs Suri), site of the dominant follicle (left or right ovary), lactation state, number of matings by the male (1 or 2), or interval between parturition and mating, did not affect pregnancy outcome. Follicles with a diameter less than 7 mm were able to ovulate in response to mating. This was smaller than previously reported. Thirty-four pregnancies (49% pregnancy rate) resulted in 30 (88%) births with a gestation length of 343 days (SEM +/- 2, range 316-367 days). There were 4 (12%) abortions between days 45 and 80 of gestation and full term.

CONCLUSION

It was not possible to correlate mating behaviour and ovarian state with conception. To optimise pregnancy rates in receptive alpacas, matings need to occur in the presence of an oestrogenic follicle that is capable of ovulation in response to mating. A simple method of detecting alpacas with follicles in this state is not currently available and treatments that control ovarian follicular growth should therefore be investigated.

Use of GnRH agonist implants for long-term suppression of fertility in extensively managed heifers and cows

The ability of gonadotrophin releasing hormone (GnRH) agonist implants to suppress ovarian activity and prevent pregnancies, long-term, was examined in heifers and cows maintained under extensive management. At three cattle stations, heifers (2-year-old) and older cows (3- to 16-year-old) were assigned to a control group that received no treatment, or were treated with high-dose (12 mg, Station A) or low-dose (8 mg, Station B and Station C) GnRH agonist implants. The respective numbers of control and GnRH agonist-treated animals (heifers + cows) at each station were: Station A, 20 and 99; Station B, 19 and 89; Station C, 20 and 76. Animals were maintained with 4% bulls and monitored for pregnancy at 2-monthly intervals for approximately 12 months. Pregnancy rates for control heifers and control cows ranged from 60-90% and 80-100%, respectively, depending on the study site. The respective number of animals (heifers + cows) treated with GnRH agonist that conceived, and days to first conception, were: Station A, 9 (9%) and 336 +/- 3 days; Station B, 8 (10%) and 244 +/- 13 days; Station C, 20 (26%) and 231 +/- 3 days. Treatment with high-dose GnRH agonist prevented pregnancies for longer (approximately 300 days) than treatment with low-dose GnRH agonist (approximately 200 days). In the majority of heifers and cows treated with GnRH agonist, ovarian follicular growth was restricted to early antral follicles (2-4mm). The findings indicate that GnRH agonist implants have considerable potential as a practical technology to suppress ovarian activity and control reproduction in female cattle maintained in extensive rangelands environments. The technology also has broader applications in diverse cattle production systems.

Control of ovulation with a GnRH agonist after superstimulation of follicular growth in buffalo: fertilization and embryo recovery

The potential to use a GnRH agonist bioimplant and injection of exogenous LH to control the time of ovulation in a multiple ovulation and embryo transfer (MOET) protocol was examined in buffalo. Mixed-parity buffalo (Bubalus bubalis; 4-15-year-old; 529 +/- 13 kg LW) were randomly assigned to one of five groups (n = 6): Group 1, conventional MOET protocol; Group 2, conventional MOET with 12 h delay in injection of PGF2alpha; Group 3, implanted with GnRH agonist to block the preovulatory surge release of LH; Group 4, implanted with GnRH agonist and injected with exogenous LH (Lutropin, 25 mg) 24 h after 4 days of superstimulation with FSH; Group 5, implanted with GnRH agonist and injected with LH 36 h after superstimulation with FSH. Ovarian follicular growth in all buffaloes was stimulated by treatment with FSH (Folltropin-V, 200 mg) administered over 4 days, and was monitored by ovarian ultrasonography. At the time of estrus, the number of follicles >8 mm was greater (P < 0.05) for buffaloes in Group 2 (12.8) than for buffaloes in Groups 1(8.5), 3 (7.3), 4 (6.1) and 5 (6.8), which did not differ. All buffaloes were mated by Al after spontaneous (Groups 1-3) or induced (Groups 4 and 5) ovulation. The respective number of buffalo that ovulated, number of corpora lutea, ovulation rate (%), and embryos + oocytes recovered were: Group 1 (2, 1.8 +/- 1.6, 18.0 +/- 13.6, 0.2 +/- 0.2); Group 2 (4,6.1 +/- 2.9, 40.5 +/- 17.5, 3.7 +/- 2.1); Group 3 (0, 0, 0, 0); Group4 (6, 4.3 +/- 1.2, 69.3 +/- 14.2, 2.0 +/- 0.9); and Group 5 (1, 2.5 +/- 2.5, 15.5 +/- 15.5, 2.1 +/- 2.1). All buffaloes in Group 4 ovulated after injection of LH and had a relatively high ovulation rate (69%) and embryo recovery (46%). It has been shown that the GnRH agonist-LH protocol can be used to improve the efficiency of MOET in buffalo.

Differential requirement for pulsatile LH during the follicular phase and exposure to the preovulatory LH surge for oocyte fertilization and embryo development in cattle

The requirement for pulsatile LH and the LH surge for the acquisition of oocyte fertilizing potential and embryo developmental competency was examined in Zebu heifers. Follicular growth was superstimulated using the GnRH agonist-LH protocol in which pulsatile LH and the preovulatory LH surge are blocked. In experiment 1, heifers were assigned on Day 7 of the estrous cycle to receive: group 1A (n = 5), 1.5 mg norgestomet (NOR) implant; group 1B (n = 5), GnRH agonist implant. Follicular growth was superstimulated with 2x daily injections of FSH from Day 10 (a.m.) to Day 13 (p.m.), with PGF2alpha injection on Day 12 (a.m.). Heifers were ovariectomized on Day 15 (a.m.) and oocytes were placed immediately into fertilization, without 24 h maturation. Respective cleavage and blastocyst development rates were: group 1A, 0/64 oocytes (0%) and 0/64 (0%); group 1B, 34/70 oocytes (48.6%) and 2/70 (2.9%). In experiment 2, heifers were assigned on Day 7 of the estrous cycle to receive: group 2A (n = 10), 1.5 mg NOR implant; group 2B (n = 10), GnRH agonist implant; group 2C (n = 10), GnRH agonist implant. Follicular growth was superstimulated as in experiment 1 above. Heifers in groups 2A and 2B received an injection of 25 mg LH on Day 14 (p.m.) and all heifers were ovariectomized on Day 15 (a.m.); oocytes were placed immediately into fertilization without 24 h maturation. Cleavage rates were similar for heifers in group 2A (84/175 oocytes, 48.0%), group 2B (61/112 oocytes, 54.5%) and group 2C (69/163, 42.3%). Blastocyst development rates were similar for heifers in group 2A (22/175 oocytes, 12.6%) and group 2B (25/112 oocytes, 22.3%) and lower (P < 0.05) for heifers in group 2C (9/163 oocytes, 5.5%). Oocytes obtained from heifers treated with GnRH agonist, without injection of exogenous LH, underwent cleavage indicating that neither pulsatile LH nor the preovulatory LH surge are obligatory for nuclear maturation in cattle oocytes. Exposure to a surge-like increase in plasma LH increased embryo developmental competency indicating that the preovulatory LH surge promotes cytoplasmic maturation. The findings have important implications for controlling the in vivo maturation of oocytes before in vitro procedures including nuclear transfer.

Embryo recovery and pregnancy rates after the delay of ovulation and fixed time insemination in superstimulated beef cows

The aim of this study was to evaluate the effect of delaying ovulation subsequent to superstimulation of follicular growth in beef cows (Bos indicus) on embryo recovery rates and the capacity of embryos to establish pregnancies. Ovulation was delayed by three treatments using either progesterone (CIDR-B) or a GnRH agonist (deslorelin). Multiparous Nelore cows (n = 24) received three of four superstimulation treatments in an incomplete block design (n = 18 per group). Cows in Groups CTRL, P48 and P60 were treated with a CIDR-B device plus estradiol benzoate (EB, 4 mg, i.m.) on Day-5, while cows in Group D60 were implanted with deslorelin on Day-7. Cows were superstimulated with FSH (Folltropin-V, 200 mg), from Day 0 to 3, using twice daily injections in decreasing amounts. All cows were treated with a luteolytic dose of prostaglandin on Day 2 (08:00 h). CIDR-B devices were removed as follows: Group CTRL, Day 2 (20:00 h); Group P48, Day 4 (08:00 h); Group P60, Day 4 (20:00 h). Cows in Group CTRL were inseminated at 10, 20 and 30 h after first detected estrus. Ovulation was induced for cows in Group P48 (Day 4, 08:00 h) and Groups P60 and D60 (Day 4, 20:00 h) by injection of LH (Lutropin, 25 mg, i.m.), and these cows were inseminated 10 and 20 h after treatment with LH. Embryos were recovered on Days 11 or 12, graded and transferred to synchronized recipients. Pregnancies were determined by ultrasonography around Day 100. Data were analyzed by mixed procedure, Kruskal-Wallis and Chi-square tests. The number of ova/embryos, transferable embryos (mean +/- SEM) and pregnancy rates (%) were as follows, respectively: Group CTRL (10.8+/-1.8, 6.1+/-1.3, 51.5), P48 (12.6+/-1.9, 7.1+/-1.0, 52.3), P60 (10.5+/-1.6, 5.7+/-1.3, 40.0) and D60 (10.3+/-1.7, 5.0+/-1.2, 50.0). There were no significant differences among the groups (P > 0.05). It was concluded that fixed time AI in association with induced ovulation did not influence embryo recovery. Furthermore, pregnancy rates in embryos recovered from cows with delayed ovulation were similar to those in embryos obtained from cows treated with a conventional superstimulation protocol.

Sustained testicular atrophy in bulls actively immunized against GnRH: potential to control carcase characteristics

The objectives were to determine whether active immunization against gonadotrophin releasing hormone (GnRH) induced a long-term suppression of testicular function in bulls, and to ascertain the effects of immunization against GnRH on carcase and meat quality characteristics. In experiment 1, 6-month-old Zebu bulls were assigned to: control (n=25), no treatment; immunized (n=31), immunized against GnRH at 0 and 4 months (anti-GnRH(2)), with a sub-set of bulls (n=17) immunized again at 10 months (anti-GnRH(3)). After the second immunization, testicular growth ceased for 2 months in 14/31 (45%) bulls and for at least 6 months in 17/31 (55%) bulls. Among the latter bulls (anti-GnRH(3)) the testes did not grow for >1 year after the third immunization in 5/17 (30%) bulls. In experiment 2, 22-month-old Zebu bulls were assigned to: control (n=14), no treatment; immunized (n=17), immunized against GnRH at 0, 2 and 4 weeks. The testes decreased (P<0.05) in size for 2 months after immunization in 11/17 (65%) bulls and then re-initiated growth, whilst in 6/17 (35%) bulls the testes continued to decrease in size for 4 months and did not re-initiate growth for 1 year. At slaughter, the latter immunocastrated bulls had carcase and meat quality characteristics the same as contemporary bulls that had been castrated before puberty. The findings demonstrated that active immunization against GnRH can induce a long-term suppression of testicular function in a proportion of bulls. Also, when bulls are immunocastrated after puberty, carcase and meat quality traits change from those typical of entire bulls to traits that are characteristic of long-term castrated bulls.