Evaluación de dos estrategias de alimentación en ganado caprino: vigorización energética (“flushing”) en hembras reproductoras y uso de Calliandra calothyrsus en cabros destetados

Abstract

In Puerto Rico and the tropics in general, the major limitations affecting goat production are low reproductive efficiency, low nutritional value of forages and high incidence of gastrointestinal nematodes. For these reasons, field experimentation was conducted. The objective of the first experiment was to evaluate the effects of energy flushing using two concentrate levels (CL) on body condition score (BCS), and body weight (BW) of breeding goats, number of kids, birth and weaning weights, and rate of weight gain of the offspring. Treatments were a high CL (600g/d of grain mixture; 1.8 Mcal ME) and a low CL (300g/d; 0.9Mcal ME) in a completely randomized design. The goats grazed native grass pastures. Flushing started 21-d prior to introduction of the buck and continued for 42-d. Thereafter, all nannies were fed a low CL until parturition. Nannies were weighed at the start of flushing, and at 9 and 96 days after introduction of the buck. BCS was estimated monthly. The kids were weighed at birth and weekly until weaning (45 days). There were no significant effects of CL (P>0.05) on BW, BCS, and kid numbers, but a tendency for higher numerical values of these variables with high CL was observed. Kid birth weight was lower with the high compared to the low CL (2.5 vs. 3.3kg). This was a result of more twinning with the high CL. There was also no effect (p>0.05) of CL on weaning weight (8.2 vs. 7.8 kg) and weekly rate of weight gain (860 vs. 727g) with the high and low CF, respectively. In conclusion, CL greater than 300g/d prior to and during the mating season did not significantly improve reproductive performance in meat goats. However, similar studies conducted in nannies with lower initial BCS than those of the present experiment or with more animals per treatment might show a benefit of the higher supplementation level. The second experiment determined Calliandra calothyrsus supplementation effects on live weight (LW) and efficacy against gastrointestinal nematodes (GIN) in weanling goats. Eight boer goats (12.4 kg) were randomly assigned to two treatments: supplementation with guineagrass hay (GH; Panicum maximum Jacq.) or with leaves and fine steams of freshly cut Calliandra (FC). Supplementation was at 20% of the expected dry matter intake (3% of LW daily). Bi-weekly the animals were weighed, feces samples were collected to determine fecal egg counts (FEC) and FAMACHA© index scores were assigned. Blood samples were taken every 21 days from individual animals to determine packed cell volume (PCV). Data were analyzed using repeated measures analysis. Supplementation with FC had no significant effect on live weight (12.6 vs. 12.4kg), FAMACHA© index (3.4 common value) and PCV (25.8% vs. 26.6%) for FC and GH, respectively. FEC was significantly lower (p<0.05) in the group supplemented with Calliandra than in that fed with GH (638.16 vs. 982.13 eggs/g). The decrease in fecal excretion of GIN eggs could have the benefit of reducing pasture GIN contamination. The objective of this last study (using data available from the second experiment), was to validate the FAMACHA© system for detecting anemia in goats under Puerto Rican conditions. The criteria used to diagnose anemia were: eye score values of 4 and 5 and PCV value ≤ 19. Sensitivity was found to be 100% and specificity 73.5%. Although there were 22.5% of false positive results and 15% of true positives, there was no false negative. This indicates that all anemic animals received antiparasitic treatment. Predictive value of a negative was 100% and of a positive was 62.5%. Significant correlations were found between PCV and FAMACHA© score (p<0.05) and between PCV and FEC (p<0.05), the respective correlation coefficients being -0.46 and -0.39. It is concluded that the FAMACHA© system is a useful tool to determine anemia in goats under local conditions.