engleski

Influence of body weight on the onset of puberty in Cameroon Dwarf goats in northwestern Croatia

Objectives: To determine the influence of body weight on the onset of puberty in Cameroon Dwarf goats (CDG) kept as pets in northwestern Croatia, progesterone and insulin like growth factor-I (IGF-I) levels were determined in blood using RIA methods. Methods: The onset of ovulatory activity was determined in ten Cameroon Dwarf goat (CDG) kids, by measuring progesterone and IGF-I plasma concentrations every 20 days from 75 to 155 days of age. Animals were weighed at the beginning and at the end of the study. IGF-I and progesterone (P4) blood levels were determined using the RIA (LKB 1261 Multigamma Gamma Counter). The start of cyclicity was determined when the observed concentration of progesterone was higher than 1 ng/mL. Statistically significant results were at p < 0.05. Results: The onset of puberty in CDG occurred at 115 days of age (DOA) in 2 goats (No. 3 and 9), at 135 DOA in 2 goats (No. 2, 7), and at 155 DOA in 4 goats (No. 4, 5, 6, 10), while 2 goats were not in heat during the study. Average body weight at the beginning and at the end of the study of goats in heat at 115 to 135 DOA was higher than of goats in heat at 155 DOA and anoestrous goats (3.70 ± 0.43 and 5.35± 0.55 ; vs. 4.60 ± 0.35 and 5.97 ± 0.46 ; vs. 5.72 ± 0.13 and 7.1 ± 0.40, respectively). The average progesterone level at 75 to 115 DOA was below 0.02 ng/mL, but was higher at 155 DOA than at 135 DOA (0.68 ± 0.88 vs. 3.89 ± 4.89, respectively). The average IGF-I level in the period from 75 to 115 DOA was lower than at 135 and 155 DOA (49.52 ± 18.86 ng/mL vs. 75.60 ± 34.44 ng/mL, respectively). Conclusions: Age at sexual maturity is a controversial point in tropical goats, with reports listing the onset of maturity between 6 and 14 months. In CDG kept as pets in Croatia, maturity occurred by 115 DOA in 20% or by 155 DOA in 90% of goats tested, which is much earlier than in previous reports. The influence of body weight on the onset of puberty in CDG was significant, as heavier CDG female kids reached puberty earlier than females weighing less.

Cammeroon Dwarf goat, body weight, puberty, Croatia

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