Suckling, male effect and kisspeptin in the reproductive management of ewes in postpartum anestrus

Objective: To describe the management strategies of controlled suckling and the male effect to reduce postpartum anestrus, and to show the participation of kisspeptin to regulate the effect of both factors. Design/Methodology/Approach: A review of scientific publications was conducted, in order to show the importance of suckling and the male effect as strategies to reduce postpartum anestrus in the ewe, as well as the relation of kisspeptin with both factors. Results: Seasonal anestrus can be avoided with the use of breeds adapted to the local environment, such as Pelibuey. Postpartum anestrus occurs mainly as a result of suckling, since the latter inhibits the pulsating secretion of the gonadotropin-releasing hormone (GnRH) and the luteinizing hormone (LH). The exact path of this inhibition is unknown, although it seems that endogenous opioid peptides and kisspeptin are intermediaries. Controlled suckling and the male effect are management strategies that improve the reproductive behavior of postpartum ewes. Kisspeptin regulates the influence of the male effect through the secretion of GnRH/LH. Study Limitations/Implications: To understand the impacts of suckling and the male effect on the duration of postpartum anestrus, as well as the participation of kisspeptin in the regulation of both effects, will allow designing management strategies to improve the reproductive efficiency of the ewes. Findings/Conclusions: Controlled suckling and the male effect reduce postpartum anestrus and improve the reproductive behavior of the ewes; advancing knowledge of the kisspeptin effect could improve the effectiveness of both techniques.

Resposta reprodutiva na apresentação de zelagem, fertilidade e prolificidade em ovelhas pelibues, sincronizadas com FGA, P4, PMSG e efeito masculino / Reproductive response on the presentation of zeal, fertility and prolificity in pelibuey sheep, synchronized with FGA, P4, PMSG and male effect

A aplicação do efeito macho (E.M.) como substituto do PMSG em ovelhas tratadas com esponjas vaginais FGA, com o objetivo de induzir e sincronizar o calor das ovelhas sem aumentar excessivamente a prolificidade, reduzindo assim o custo do tratamento. Para tanto, foram utilizadas 60 ovelhas da raça pelibuey, divididas aleatoriamente em três grupos: grupo 1 (Controle): o protocolo foi o clássico, utilizando uma esponja APG vaginal em dose normal (40 mg, Cronogest®, Intervet) durante 11 dias. PMSG (500 IU.IM.) foi injetado 2 dias antes (dia 9) da remoção da esponja. O grupo foi mantido isolado dos machos até o dia do acasalamento dirigido. Grupo 2: apenas ½ esponja FGA (20mg. Cronogest®, Intervet) sem PMSG foi usada. No dia 5 foi injetada progesterona (25mg, IM em solução oleosa) e no dia 8 o "efeito masculino" foi causado. Grupo 3: Com apenas ½ esponja FGA (20mg, Cronogest®, Intervet) também injetando progesterona (25mg, IM em solução oleosa no dia da inserção da esponja) sem PMSG, por 6 dias. Três dias antes (dia 3) da remoção da esponja, o "efeito masculino" foi obtido. Os ovinos dos grupos G1, G2 e G3 não mantinham contato com os machos há 30 dias. Um macho foi usado para detecção de cio e mais dois para acasalamento. O grupo controle foi superior apenas no tempo de apresentação do calor em relação ao G2 e G3 com diferença estatística (p 0,05). Para as variáveis de fertilidade e prolificidade, não houve diferenças significativas (p 0,05) entre os três grupos. Esses resultados demonstram as grandes possibilidades de utilização do efeito macho ao invés do PMSG para sincronização de calor em ovinos.

Factors Associated with the Onset of Ovarian Activity of Cattle Commonly Reared in the Huasteca Veracruzana, Mexico

Objective: To identify the factors that affect the onset of ovarian activity in prepuberal heifers in the Huasteca Veracruzana of Mexico.Design/Methodology/Approach: Samples were taken from animal production units of the municipality of Tantoyuca, Veracruz. The onset of ovarian activity was determined by the presence of ovarian follicles andncorpus luteum by ultrasonography technique. Zoometric indices and body condition were calculated at them same time, and the zootechnical practices that were applied to the animals in the last six months before thesampling day were registered. A survey was applied to characterize the management of animal productionunits; the main topics in the survey were: health, reproduction, nutrition, and suckling. All animals available within selection criteria in the production units were sampled. A multiple linear regression (Statistical Analysis Software Version 9.4) and cluster analysis (R Studio Version 1.1.419) were used to identify the main categorical variables that affected the model.Results: The onset of ovarian activity depends mainly on the anatomical development of the heifers. The biostimulation (male effect) on the heifers has an important effect on reducing the age at puberty.Study Limitations/Implications: The study was developed during a long drought period in the region.Findings/Conclusions: The genetic mosaic of the evaluated animals in the production units did not affect the onset of ovarian activity of the heifers; however crossbred heifers (Bos taurus ? Bos indicus) begin the ovarian activity younger.

Photoperiod-Treatment in Mediterranean Bucks Can Improve the Reproductive Performance of the Male Effect Depending on the Extent of Their Seasonality

This study examines the effectiveness of the photoperiod treatment (extra light for 88 days) to render the bucks sexually active during the seasonal anoestrous in order to induce a male effect, depending on the reproductive seasonality of the breed of the bucks used. In April, 57 anoestrous Blanca Andaluza does were distributed into four groups with three males each: 13 were exposed to control Murciano–Granadina bucks (lower seasonality); 15 were exposed to photostimulated Murciano–Granadina bucks; 14 were exposed to control Blanca Andaluza bucks (higher seasonality), and 15 were exposed to photostimulated Blanca Andaluza bucks. After male introduction, the sexual behaviour of the bucks was assessed, and harness marks recorded doe oestrous behaviour. Ovulation was confirmed from plasma progesterone, and the ovulation rate was assessed by transrectal ultrasonography. Fecundity, fertility, prolificacy and productivity were also determined. All of the does in all of the groups showed ovulation. Interaction between both sources of variation was observed: the percentage of females showing oestrous (p < 0.01) and productivity (p < 0.05) was the lowest in the Blanca Andaluza control group (50% and 0.36 ± 0.17 goat kids born/female, respectively). In conclusion, photoperiod-treated bucks efficiently induce a male effect, but photostimulation could be more necessary for breeds with deep seasonality.

Influence of male on estrus behavior, estradiol and progesterone release and puberty onset on prepubertal Saanen goats

The present study investigated the male effect on the estrus behaviors, estradiol and progesterone release in prepubertal Saanen goats. Twenty-nine female Saanen goats at 135 ± 10 days old with body weight of 22.8 ± 3.3 Kg were randomly assigned to three treatments: exposure to sexually active male (male treatment), exposure to androgenized females (androgenized female treatment), and prepubertal goats isolated from active male and androgenized females (control treatment). Sexual behaviors associated with estrus were recorded daily, and blood samples were taken weekly to determine estradiol and progesterone concentrations over 24 weeks. The experimental goats subjected to male or androgenized female had significantly higher frequency of estrus (mount acceptance) (P ? 0,02), progesterone (P ? 0,01), and estradiol (P ? 0,01) release than the control goats. Furthermore, goats exposed to a male showed estrus behavior two weeks earlier and maintained this estrus behavior for three weeks more than goats of both female and control treatments. Estrus was observed in 70 % of goats in male and female treatments during the breeding season versus 44 % of the control goats. Finally, significantly more goats subjected to male treatment (60 % of goats) showed progesterone concentrations higher than 1 ng mL-1 (which indicates the presence of a functional corpus luteum) compared to the female and control treatment (40 and 22 % of goats, respectively). These results shows that male treatment significantly increased the number of females showing estrus behavior, estradiol and progesterone release, and the number of animals with a functional corpus luteum, anticipating puberty for experimental goats, suggesting that the male effect could be used to anticipate the onset of puberty in goats.