Lactation and Function of Curve Parameters in Yankasa Sheep

Abstract

The accuracy of the gamma function to describe lactation curve of Yankasa ewes was investigated using milk production data obtained from 168 ewes with either complete or incomplete 84 day lactation records. Ewes were daily hand milked after over-night separation from lamb and thorough disinfection of the udder. The daily milk yield on the average was estimated from the weekly total yield. The effect of type of birth, parity, season of birth and lactation length on the components of lactation curve (a, b, c and s) were analysed by least-square procedures. All factors except parity significantly (p<0.01) influenced the curve parameters. The goodness of fit of the function did not differ between the two classes of varying duration of lactation; incomplete lactation however, showed a lower persistency and as expected lower level of production. Correlations (r p ) between lamb weight gain and milk yield using the weight records from lamb weighed at weekly intervals indicated a high and positive relationship in the early lactation that decreased in intensity as the lactation advanced.

The application of a mechanistic model to analyze the factors that affect the lactation curve parameters of dairy sheep in Mexico

“…Previous studies have reported higher milk yields of sheep carrying twins in comparison to singles (Afolayan et al, 2002;Gootwine and Pollott, 2000). Higher MSmax values of ewes bearing twins could explain, although showing only a trend (P = 0.09), the observed differences in milk production between single and twin-bearing ewes.…”

Lactation curve, milk production of Pelibuey ewes and preweaning growth rate of the lambs

“…However, it differs from the results by Peniche et al (2015), Allah et al (2011), andPeralta-Lailson et al (2005) in terms of the dates of time until the peak of lactation, since in these studies the dates were weeks seven, five and one, respectively. These differences Afolayan et al (2002) also found that the parameters a, b, and c were higher in ewes with two lambs, which suggests that the number of lambs suckled by the ewe has an important influence on the MP, which has been found before in other sheep breeds (Snowder and Glimp, 1991). On the other hand, Afolayan et al (2002) the parameters of Wood's model that have been estimated in dairy ewes are a0.…”

“…These differences Afolayan et al (2002) also found that the parameters a, b, and c were higher in ewes with two lambs, which suggests that the number of lambs suckled by the ewe has an important influence on the MP, which has been found before in other sheep breeds (Snowder and Glimp, 1991). On the other hand, Afolayan et al (2002) the parameters of Wood's model that have been estimated in dairy ewes are a0. 979, b0.071, c0.009 (Ángeles-Hernández et al, 2013), a1,333, b0.3, c0.092 (Miguel et al, 2016; in these studies, the magnitude of parameter a standout, which represents milk production at the beginning of the lactation, indicating specialized breeds in milk production.…”