No abstract

No abstract

This study was designed to determine the effect of location of the preovulatory dominant follicle and stage of ovarian follicle development on ovulation rate and embryo survival in alpacas. In Experiment 1, mature lactating alpacas were randomly assigned to one of two groups according to the location of the dominant follicle detected by ultrasonography: (a) Right ovary (RO, n=96) or (b) Left ovary (LO, n=108). All females were mated once by an intact adult male. Ovulation rate, CL diameter and embryo survival rate (heartbeat) were assessed by ultrasonography on Days 2 (Day 0=mating), 8 and 30, respectively. Ovulation rate (96.5 and 96.3% for RO and LO group, respectively), corpus luteum (CL) diameter (10.2 and 10.6 mm for RO and LO group, respectively) and pregnancy rate (60.2 and 56.7% for RO and LO group, respectively) did not differ among groups. In Experiment 2, lactating alpacas (n=116) were submitted to ultrasonic-guided follicle ablation to synchronize follicular wave emergence. Afterwards, daily ultrasonography examinations were performed and females were randomly assigned to the following groups according to the growth phase and diameter of the dominant follicle: (a) early growing (5-6 mm, n=27), (b) growing (7-12 mm, n=30); (c) static (7-12 mm, n=30), or (d) regressing phase (12-7 mm, n=29). All alpacas were mated with a proven intact male, except five alpacas from early growing group that rejected the male. Females were examined by ultrasonography on Day 2 (ovulation rate), Day 8 (CL diameter), and Days 15, 20, 25, 30 and 35 (embryo survival by the presence of embryo proper and heartbeat). No differences were detected in ovulation rate among groups (96%, 97%, 100%, and 97%) or in CL size (10.3, 11.7, 11.1, and 11.1 mm, for early growing, growing, early static and regressing, respectively). Although, embryo survival rate at Day 35 after mating was numerically greatest in growing (65.5%), intermediate in early growing (52.4%) and static (53.3%), and least in regressing phase (42.9%), there were no differences among groups. Results suggest that neither location nor stage of development of the dominant follicle has an influence on ovulation and embryo survival rate in alpacas.

ABSTRACT.A poor nutritional state may explain the low fertility rates of domestic camelids from Puna herds. The objective of this study was to determine the relationship between the nutritional state of alpacas before the breeding period and their reproductive success. The body live weight (BLW) and body condition score (BCS; scale from 1-5) of 35 non-pregnant non-lactating alpacas from the Caquena bofedal in Chile were registered previous to the breeding period. In addition, blood samples were collected (heparinised tubes) to determine the plasma concentration of cholesterol (CHOD-PAP method), triglycerides (GPO-PAP method) and NEFA (enzymatic colorimetric method). Pregnancy was determined by trans-rectal ultrasonography (7.5 MHz, Samsung Madison, Korea) at the end of the breeding period. Data from Pregnant and Non-Pregnant groups were compared using Mann-Whitney U test (SPSS programme; P< 0.05). Pregnant (n=20) and Non-pregnant groups (n=15) had similar BLW (47.1 ± 8.8 compared to 52.8 ± 11.1 kg, respectively; P = 0.9), BCS (3.0 ± 0.4 compared to 3.1 ± 0.4, respectively; P = 0.5), plasma cholesterol (1.0 ± 0.4 compared to 0.9 ± 0.3 mmol/l, respectively; P=0.7), triglycerides (0.3 ± 0.1 compared to 0.4 ± 0.1 mmol/l, respectively; P = 0.3), and NEFA (0.6 ± 0.4 compared to 0.8 ± 0.6 mmol/l, respectively; P = 0.1) before the breeding period. NEFA values of both groups showed evidence of negative energy balance. The nutritional state of alpacas before the breeding period did not explain the differences obtained in their reproductive success.

Energy unbalance may be the cause of low fertility rates found in vicuñas. The objective of this study was to estimate the temporal variation of the nutritional status in pregnant vicuñas from a herd kept under captivity in the Chilean High Andes. The hypothesis under study is that animals are able to maintain the energy balance during the dry season. Six pregnant vicuñas were examined in August, October and January (year 2015-2016). Reproductive status was estimated by ultrasonography and plasma progesterone concentration. Live weight (LW) and body condition score (BCS: 1-5 scale) were measured for each animal. A blood sample was taken to estimate the plasma concentrations of total protein (Biuret method), cholesterol (CHODPAP method), triglycerides (GPO-PAP method), β-hydroxybutyrate (enzymatic method) and non-esterified fatty acids (NEFA; enzymatic colorimetric method). Vicuña groups had similar LW, BCS, plus similar plasma concentrations of metabolites, total protein and progesterone. Females did not increase their LW during gestation and their BCS in January (2.9) was below the recommendations for late pregnancy in camelids (BCS 3.5). NEFA and β-hydroxybutyrate values were higher than those expected under nutritional energy balance signalling a lipolytic and ketogenic metabolic response, respectively. The absence of weight gain and the values of NEFA and β-hydroxybutyrate show that pregnant vicuñas suffer a negative energy balance during the dry season in the Chilean High Andes. This can cause abortion and contribute to low fertility rates of the herds. It is suggested to provide pregnant vicuñas with food supplements up to birthing, in years of severe drought.