Gregory Bourne’s research while affiliated with University of the West Indies, St. Augustine and other places

The objective of this study was to evaluate serum progesterone (P4) and 17β estradiol (E2) concentrations throughout the estrous cycle in the red-rumped agouti (Dasyprocta leporina). A total of eight multiparous, captive-bred females were bled throughout their estrous cycle via saphenous venipuncture, with E2 and P4 concentrations being measured via ELISA of the serum collected. Serum E2 ranged from 1212–3500 pg/ml with a peak value coinciding with observed estrus. However, two additional peak values for E2 were also recorded, one each in metestrus and proestrus respectively. P4 concentrations reached a maximum of 4.23 ng/ml, and increases in P4 immediately followed the second E2 peak in metestrus. The highest concentrations of P4 were recorded in mid diestrus; between days 23-25 of the 31-day cycle. This phase was the longest in the agouti, consisting of approximately 19 days and accounted for 61% of the cycle. This study increased the basal scientific reproductive knowledge of this potentially valuable neo-tropical species.

Animal management for breeding and marketing can be improved by precise measurement of desirable traits. Live animal body composition analysis facilitates the selection of animals that are best suited for the intended purpose. This study was designed to assess the accuracy of bioelectrical impedance analysis (BIA) predicted live body tissue composition, as a proxy for the estimation of carcass quality in Barbados Black Belly lambs. Thirty-four Barbados Black Belly lambs were placed on an 8-week feeding regime and then slaughtered. A randomized experimental design was used to allocate diets to animals, which had been stratified into eight groups by initial live weight. The lambs were fed a basal diet of Brachiaria arrecta fresh forage ad libitum and subjected to one of four diets; NS-non-supplemented diet, TG-Trichantera gigantea-supplemented, C100-concentrate supplemented for maintenance, and C400-concentrate supplemented for growth. Diets NS, TG, C100, and C400 had 7, 9, 11, and 7 animals, respectively. The average age and weight at the time of slaughter were 206 days and 23.7 kg, respectively. A 4-terminal impedance analyzer (RJL Systems®) was used to generate BIA data from live animals immediately before slaughter. The chilled carcasses were then subject to chemical analysis for crude fat, crude protein, and dry matter. Live animal and carcass traits predicted by BIA included fat and fat-free mass, crude fat, crude protein, protein to fat ratio, and tissue distribution. Regression equations were developed from BIA data obtained from the live animal to predict all carcass composition traits measured. Bioelectrical impedance analysis generated favorable results as a practical application to carcass composition evaluation in live tropical hair sheep.

The agouti/cutia/picure/kokoni/indian rabbit is one of the most widely distributed of the Neo-tropical animals. Today, it can be found from northern Mexico in Central America down to Argentina in South America and on most Caribbean Islands, with the exception of Antigua, Bahamas, Barbuda, Barbados, Jamaica and Nevis. Archaeological evidence has indicated that it existed on many of the sites within the Caribbean and it was found as far north as Antigua up to 2000 years ago. The agouti is the third largest rodent within the Neo-tropics [Capybara Hydrochoerus hydorchaeris) ~ 60kg, Paca (Agouti paca) ~12kg, and Agouti (Dasyprocta leporina) ~2.4kg]. It is prized for its meat that retails in Trinidad and Tobago at $50-50 YYF ot$8-12 USD per kilogram. The agouti has been reported to produce from 1-5 precocious young per litter, with 3 parturitions per year (every 127 days). Our experience has ranged from 1-5 young/litter, with only a maximum of 3 surviving. The animal has 4 pairs of mammary glands and all have been found to be functional. The agouti is a frugivore with a caecum that accounts for 16% of the digestive system. This means that the animal can be fed exclusively on Neo-tropical fruits and crops and as it is a rodent, feed processing or particle size reduction is not necessary. As a result, a model is being proposed to integrate agouti production with the production of Neo-tropical fruits and food crops so that value-added could be given to the wasted portions and non-marketable produce. In this way, agouti farming can be linked into agro-tourism and eco-tourism products.

The effects of time of weaning on subsequent reproductive performance of ewes and the growth of lambs were evaluated in Barbados Blackbelly hair sheep, under a tropical photoperiod. Two experiments were conducted to assess the effect of time of weaning on subsequent reproductive performance of the ewe. In Experiment 1, lactating ewes (n=56) were weaned early (WE1; 72.6±1.3 days postpartum; n=31), 21 days prior to introduction to the rams (RI) – or not weaned prior to the breeding period, but temporarily removed from their lambs (n=25) for 3 days – beginning at ram introduction and then weaned 24 days later (TSE1; 121.2±1.3 days postpartum). In Experiment 2, ewes were either separated from their lambs (n=29), 17 days prior to ram introduction (RI; WE2; 75.7±1.2 days postpartum) remained with their lambs during the entire breeding period (UW; n=16), or their lambs temporarily removed for 3 days – beginning at ram introduction (RI) and then re-joined with their dams (n=13; TSE2). The proportion of ewes lambing, interval from RI to lambing, lambing day during lambing period and prolificacy were not affected by treatment. The lambing interval recorded was longer in late weaned ewes in Experiment 1, but time of weaning had no effect in Experiment 2. To assess the effect of time of weaning on lamb growth, two experiments were conducted in which lambs were weaned either early (EW; 76 or 108 days of age for Experiments 1 and 2, respectively) or late (LW; 186 and 159 days of age for Experiments 1 and 2, respectively). Lambs were weighed at birth, at weaning and at monthly intervals until 1month following the separation of the late weaned animals from their dams. The effect of time of weaning on ADG showed a significant quadratic period×treatment interaction (P

The profitability of growing-finishing lamb enterprises is plagued by the increasing cost of imported feed resources. This study was designed to assess the effect of different protein sources at different inclusion levels on growth performance and carcass quality traits of intact growing-finishing Barbados Black Belly lambs. The diets offered included tanner grass (Brachiaria arrecta) fed ad libitum supplemented with either Trichanthera gigantea (TG) leaves or one of two commercial concentrate rations (CONC100 and CONC400). Weekly growth performance was measured, followed by carcass evaluation upon slaughter after 8 weeks. Supplementing tanner grass resulted in higher weight gains in sheep (NS-16g/day vs. TG -9g/day), however, the two commercial concentrate diets promoted higher growth rates than TG leaves (43g/day and 69g/day). Trichanthera gigantea and concentrate fed at similar levels to satisfy dietary protein requirement for maintenance yielded similar carcass quality. The higher level of concentrate supplementation (CONC400) promoted greater carcass weight (12.6 kg vs. 8.2 kg) and quality. The study concluded that despite the decline in growth performance TG can replace commercial concentrate in the diet of growing-finishing lambs, with no decline in carcass quality.

Pre-wean performance of lambs from Barbados Black belly (BB) and West African (WA) type ewes managed at pasture at the Blenheim Sheep Multiplication and Research Project was studied. Lamb pre-weaning performance was analysed for the period 1999 to 2004. Birth weight, weaning weight and pre-weaning growth rate of lambs were analysed according to the GLM procedure. The fixed effects in the model were year of birth, season of birth, season of conception, birth type, sex and breed. Significant differences (P<0.05) were observed between year, sex and birth type for the parameters birth weight, pre-weaning average daily gain and weaning weight. There were no significant differences (P>0.05) between WA and BB for birth weight (2.78 vs. 2.71 kg), weaning weight (12.26 vs. 11.69 kg) or pre-weaning growth rate (124 vs. 115 gd -1), respectively. Season of birth effect was significant (P<0.05) for birth weight and pre-wean average daily weight gain but not weaning weight (P>0.05). Temperature humidity index (THI) was significantly (P<0.05) higher in the wet compared to the dry season 79.60 (±0.13) vs 77.98 (±0.24), respectively. Litter size distribution by season indicated that there was only a 4.1% reduction in litter size in the dry season. Rectal temperature (RT), respiration rate (RR), and infrared thermography were used to assess the thermoregulation of ewes in the wet season. Rectal temperatures and respiration rate (br min -1) were taken at 8:00AM before they went out to pasture and at 3:00PM when they returned. Rectal temperature and RR data were subjected to repeated measure analysis. Both types showed no significant difference (P>0.05) with regards to their thermoregulatory processes, with the exception of RT which was higher (P<0.001) for WA in the afternoon. Rectal temperature for BB and WA was 38.34 and 38.41 o C in the morning whereas it was 39.14 and 39.45 o C in the afternoon, respectively. Barbados Black belly showed a 2.8 fold increase in RR when they returned from pasture compared to 3.0 fold increase for WA ewes. Heat was lost in the facial area and underbelly and between the legs in the morning and when they returned from pasture in the afternoon heat lost was observed throughout the entire body surface including facial areas. It was concluded that although these breed types are well adapted to this tropical climatic region, better pasture management needed to be implemented to improve thermoregulation of these ewes at pasture as the environmental impact of climate on pre-wean performance of lambs produced from these ewes remains a limiting factor.

Anglo-Nubian and Saanen goats were imported into Trinidad and Tobago to form the nucleus of the goat expansion and improvement programme. Thermoregulation and performance of the parent stock and the F1 were evaluated under intensive housing and management. Rectal temperature in the A.M.: irrespective of breed or season ranged from 38.5°C to 38.7°C and P.M.: ranged from 38.8°C to 39.0°C. After 2 h of exposure outdoors without shade, Saanen parent stock (SAPS) respiration rate (105 br/min) was significantly higher (p < 0.001) than Saanen F1 (SAF1, 76 br/min), Anglo-Nubian parent stock (ANSP, 65 br/min) and Anglo-Nubian F1 (ANF1, 51 br/min). Rectal temperature over the same period showed significant differences (p < 0.042) between SAF1 (39.8°C) and SAPS (39.4°C), and ANF1 (39.4°C); the value for ANSP was 39.7°C. Age at first kidding showed no significant difference (p > 0.05) between breeds or between the parent stock and the F1 generations, ranging from 638 to 686 days. The ANPS were the most prolific of all groups (p < 0.05); the mean for this group was 1.86 ± 0.07 kids/kidding. Saanen F1 was the least prolific among the group, with mean number of kids at 1.23 (±0.11) kids/kidding. Kidding interval showed no significant (p > 0.05) difference between the groups, ranging from 319 to 521 days. It was concluded that the Anglo-Nubian appears to be more suitable than the Saanen for the tropical humid environment in Trinidad as indicated by their thermoregulation, prolificacy and kidding interval.

The efficacy of using a low cost system for delivering progesterone as part of an estrous synchronization protocol in sheep was evaluated. In experiment 1, Barbados Black Belly ewes (n=34) and ewe lambs (n=35; 37.5±0.9 kg) were assigned to be untreated, control animals (C), or to receive PGF(2α) on d0 (PG), or receive two injections of progesterone (200mg, i.m. each) on D -5 and on D -2.5, prior to PGF(2α), on D 0 (2PPG). Treatment with 2PPG increased the proportion of animals lambing to the first service (P<0.05), an effect that was greater in ewe lambs than ewes (treatment × parity; P<0.05). The interval from ram introduction to lambing and the mean lambing day was less (P=0.04) in the 2PPG-treated animals compared to control animals. In Experiment 2, lactating ewes from experiment 1 (n=61) 60-85 days postpartum were assigned within parity and number of lambs reared to remain nursing (S; n=29) or weaned (W; n=32) 3 weeks prior to treatment with the 2PPG protocol. There was no effect of treatment on the proportion of animals lambing to the first service or overall, interval from ram introduction to lambing and lambing interval. An 8-month lambing interval was observed in ewes in which estrus was synchronized regardless of physiological state. In conclusion, the two-progesterone injection synchronization protocol may be used as a practical low cost and efficient method of synchronizing estrus to reduce the lambing interval and maximize productivity in tropical breeds of sheep.

Vaginal cytology as a method of estrous determination in the female agouti (Dasyprocta leporina) - Volume 1 Issue 2 - Michele Singh, Gary W. Garcia, Andrew O. Adogwa, Gregory Bourne

Thermoregulation of Barbados Black belly and West African type ewes and seasonal effects of climate on pre-weaning performance of lambs reared under a pasture based system in a tropical environment - Volume 1 Issue 2 - Dean Avril, Cicero H. O. Lallo, Kieshel Percy, Gregory Bourne, Paul Thomas, Ruby Warner