DETERMINATION OF LACTATION CURVES IN DAMASCUS GOATS AND ASSESSMENT WITH REGARD TO HERD MANAGEMENT PRACTICE Authors: Isa Yilmaz, Ali Can, Orhan Karadag Journal: Journal of Animal and Plant Sciences (JAPS) ISSN: 1018-7081 (Print), 2309-8694 (Online) Volume: 36 Issue: 5 Year: 2026 DOI: https://doi.org/10.36899/JAPS.2026.5.0113 URL: https://doi.org/https://doi.org/10.36899/JAPS.2026.5.0113 Publisher: Pakistan Agricultural Scientists Forum Abstract:

Lactation curves not only provide information on the temporal development of milk production in a herd during a specific lactation cycle, but also on the effects of care and feeding conditions and physiological status on milk yield. The aim of this study was to describe the lactation curve of Damascus goats and to determine the effects of herd management on lactation performance. In the study conducted in 2019, a total of 620 lactation records from 62 dairy goats of different ages and lactation orders kept under semi-intensive conditions were analyzed using Wood's gamma curve parameters. Since the gamma curve parameter intercept lnA was negative for all lactation groups, the analyzed lactations showed abnormal lactation curve characteristics. The coefficients of determination (R²) of the lactation curves were 73.0 %, 72.5 %, 60.5 % and 61.7 % for the first, second, third and the average of all lactation groups. Therefore, the gamma function adequately described the lactation curves. The gamma curve parameters, including the intercept (lnA), slope coefficient (b), peak coefficient (c), persistency (S), time at which milk yield reached its maximum (Tmax), and maximum daily milk yield (Ymax), were -2.53±0.16, 1.116±0.04, 0.015±0.00, 8.88±0.13, 73.67±1.34, and 3.31±0.06, respectively. Lactation order had a significant effect on the peak coefficient (c, p ≤ 0.05) and on the maximum daily milk yield (Ymax, p ≤ 0.01). In addition, the effects of litter size were significant on b (p ≤ 0.05) and lnA, S and Tmax (p ≤ 0.01). The study of lactation curves of Damascus goats suggests that standardized feeding programs are associated with sustained high milk yield in the Iğdır region; however, causal conclusions cannot be drawn from this observational study.

Keywords: Damascus goat, lactation curve, Wood’s model, management