ABSTRACT The effect of a dose of GnRH administration at sponge insertion on pregnancy rate and litter size in ewes was investigated. A total of 162 pluriparous, non-lactating Huyang ewes (3–4 years old, 40–50 kg body weight, 120–150 days postpartum) were randomly and equally assigned to three groups (n = 54 each): control, G25, and G50. Estrus was synchronized using an intravaginal sponge impregnated with flurogestone acetate for 12 days, followed by an injection of 330 IU of equine chorionic […]

ABSTRACT The objective of this study was to compare reproductive performance and progesterone (P4) concentration in serum of synchronized ewes with new and reused (up to five times) CIDR in five-day protocols. Two experiments were conducted in the reproductive season, in two consecutive years. In experiment 1: 125 µg of PGF2α and 200 IU of eCG were applied at removal of the CIDR: CIDR1-200 (new intravaginal devices, control), CIDR2-200, CIDR3-200, CIDR4-200, and CIDR5-200 (groups with CIDR from second to fifth […]

ABSTRACT This study investigates whether pre-pubertal scrotal circumference (SC) and anti-Müllerian hormone (AMH) concentrations indicate sexual precocity in Brahman and Simmental bulls. Fifty-three bulls (Brahman, n = 27; Simmental, n = 26) were used. Scrotal circumference was measured at three periods: pre-puberty (Brahman = 19.99±0.20 months; Simmental = 9.13±0.17 months), puberty (Brahman = 21.42±0.20 months; Simmental = 18.26±0.17 months), and post-puberty (Brahman = 33.34±0.55 months; Simmental = 24.07±0.17 months). A single sample taken at the pre-pubertal period was used for […]

ABSTRACT The objective of this study was to characterize the sexual development of 48 Nelore bulls by associating the findings of sperm analyses with growth traits and ultrasound-measured testicular traits. Bulls were evaluated from 14.3 to 24.6 months old at intervals of 28 days, totaling 12 observations per animal. Data were subjected to repeated-measures analyses of variance over time (PROC MIXED, SAS 9.2) and equations for semen traits were developed using stepwise regression (PROC REG, SAS 9.2). Regarding the growth […]

ABSTRACT The objective of the study was to characterize differences in the time to onset of puberty and reproductive variables between East Friesian and Corriedale ewe lambs in an extensive pastoral system. The study was carried out for two consecutive years, and 73 pure-breed ewe lambs were evaluated (35 East Friesian and 38 Corriedale). Plasma progesterone was determined weekly between 4.5±0.5 and 7.2±0.5 months old. The time to onset of puberty was assumed when the progesterone levels were ≥0.6 ng/mL […]

ABSTRACT The objective of this research was to determine the influence of heat stress, using the temperature-humidity index (THI), on the production and quality of native sperm of bulls. The effect of heat stress on the quantity of semen (mL), density of ejaculate (number of spermatozoa, 106/mL), gross sperm motility (1-5), number of frozen doses, and motility after freezing was analysed in 1,017 sperm samples taken from 32 Holstein-Friesian bulls, in the 2017-2019 period, at the Centre for Reproduction and […]

ABSTRACT This study examined the impact of a 37.5 °C temperature on chick embryos during the hatching period (18-21 days of incubation) and its subsequent effect on hatchery results and the thermotolerance of broiler chicks from 28-40 days of rearing. For hatchery results, the study involved 16 trays per treatment. For performance, the study involved 360 broiler chicks from two distinct hatching temperature conditions: a control group (36.5 °C and 65% relative humidity (RH)) and a thermal manipulation group (37.5 […]

ABSTRACT The objective of this study was to identify parameters, before the start of the breeding season, that affect the conception rate of precocious Nelore heifers through ultrasonographic ovarian evaluation and evaluation of weight and body condition score (BCS). A total of 407 heifers aged 404±69 days (≈14 months old), weighing 267.1±31.2 kg, and with mean BCS of 3.1±0.5, were used. Heifers were subjected to hormone treatment to induce cyclicity and, 30 days later, to a fixed-time artificial insemination (FTAI) […]

ABSTRACT The objective of this study was to evaluate the effects of cocoa meal in feed concentrate on the spermatogenesis in sheep. Twenty-five uncastrated males were divided into four groups and fed concentrated feed, supplemented with 0, 10, 20, and 30% cocoa meal, respectively, for 150 days. At the end of this period, the animals were slaughtered, the testicles were collected for histological slides, and testicular morphometric assessments were conducted, including cell type quantification in the seminiferous epithelium, intrinsic spermatogenesis […]

ABSTRACT The objective of this study was to determine the impact of metabolic changes occurring in induced subclinical gestation toxaemia in ewes on metabolic parameters and vigour in the first 72 h of their lambs’ life. Fifty-one adult Corriedale ewes of known gestation date and fed on a natural pasture were randomly divided into four groups at day 145 of gestation. Group A (ewes with single pregnancies) and group C (ewes with twin pregnancies) were fed on a natural pasture […]