Seasonal semen quality of a local and commercial taurine cattle breeds, raised in a subtropical climate: Relationship between external morphology of the animals and climate.

Livestock production is considered an important factor influencing global warming; however, climate change has also been considered one of the major factors affecting livestock production and reproduction. The present study was carried out in the Southern region of Brazil and aimed to assess the seasonal influence of climatic factors and external morphology of the animals on the semen quality. Three ejaculates were obtained from each bull (Crioulo Lageano and Angus) in summer and winter seasons. Motile cells, sperm vigor, sperm concentration, sperm membrane status, and sperm abnormalities were analyzed in fresh and post-thawed semen. In addition, the sperm kinetics using CASA was assessed on post-thawed semen. Environmental data such as air temperature (AT), relative humidity (RH), mean radiant temperature (MRT) and temperature-humidity index (THI) were measured. Furthermore, body and testicular metrics, as well as hair coat characteristics, were recorded in each season on all bulls. Environmental traits differed significantly between seasons. Results of the PLS regression and Spearman's correlations confirmed a negative relationship between climatic variables and sperm traits in both seasons. Semen quality between breeds and seasons was similar, satisfactory, and heat stress was not sufficient to impair spermatozoa viability. External morphological traits were considered non-important in the final model. The findings of this study suggest that AT, MRT, and THI were the most important factors that could affect seminal characteristics of bulls raised in a subtropical climate.

Fixed-time artificial insemination protocols on brazilian locally adapted breed gilts on ovulatory response and embryo production.

The aim of this study was to use estrus synchronization protocols to favor fixed-time artificial insemination and consequently fixed-time embryo collection, and increase embryo production using eCG, in gits. In a cross over design, nine Piau breed gilts were subjected to 18 days of oral progesterone; P4 group did not receive any further; GnRH group received 25µg of GnRH 104 hours after the final application of P4; and eCG+GnRH group received 1000IU of eCG 24 hours after the final P4 in addition to GnRH for subsequent embryo collection, that was performed six days after first AI, by laparotomy. Artificial insemination was performed after 12 and 24 hours of estrus in P4 group, and 128 and 144 hours in GnRH and eCG+GnRH groups. The number of CL (8.6±3.9; 8.3±2.1; 26.7±15.0) and anovulatory follicles (4.3±3.7; 3.9±3.9; 17.2±9.5) was higher in the eCG+GnRH gilts (P<0.05). However, the use of 1000 IU of eCG reduced (P<0.05) the number of total structures (5.2±3.6; 5.1±3.1; 1.7±2.7), viable embryos (5.0±3.5; 4.8±3.3; 0.4±0.7), freezable embryos (3.6±3.4; 3.3±3.8; 0.1±0.3) and recovery rate (63.7±38.9; 58.6±24.7; 5.38±9.5). P4 and GnRH protocols were effective in the production and recovery of embryos. However, the use of 1000 IU of eCG, 24 hours after P4, was not effective in promoting the production of embryos, although the animals had superovulated.

Synchronization of follicular wave emergence does not improve embryonic yield in superovulated ewes.

The present study aimed to investigate the effects of a combination of progesterone with different doses of E-17ß on following end points: (1) ovarian follicular dynamics and emergence of a new follicular wave, and (2) superovulatory response and embryo yield. In Experiment 1, 28 ewes were randomly divided into four groups (n = 7) to receive either 2.0 mg, 1.0 mg, 0.5 mg or none E-17ß one day after insertion of a progesterone device. The different doses of estradiol similarly delayed the moment of follicular emergence (overall mean = 3.1 ± 1.0 days vs. control group = 0.86 ± 1.0 days; P < 0.01), but the emergence of the new wave showed greater synchronization with the 0.5 mg dosage of E-17ß. In Experiment 2, sixty-two donor ewes received an internal progesterone release device (day -1) for 7 d and 1 d after the insertion of this device (day 0) were allocated randomly to receive 0.5 mg of E-17ß or only the vehicle (control group). Superstimulation was initiated on day 3 with the administration of 133 mg of pFSH in eight decreasing doses. Contrary to expectations, the protocol with the administration of 0.5 mg E-17ß did not improve the percentage of donors with > 2 CL, the number of CL and the production of embryos (P > 0.05). It was concluded that the combination of progesterone and 0.5 mg E-17ß was more efficient in synchronizing the emergence of the new follicular wave, however this approach seems to be unnecessary in ewe's superovulation programs.