Milk yield adjustments for milking length and age-parity-lambing month interaction in Sarda dairy sheep

Abstract

-Milk yield adjustments for milking length and age-parity-lambing month interaction were estimated to allow effective comparisons between yields and with the perspective of improving the reliability of the genetic evaluation of Sarda dairy ewes. The

Comparison of selection criteria for milk yield traits of Valle del Belice dairy sheep

“…The genetic correlations reported in Table 3 confirm that the prior correction has removed mainly the environmental part of variation in common with LL, which is in agreement with results of Carta et al (1998) correlations of TMY, with CMY and MYH show that these last two traits can be used as alternative selection criteria for estimating breeding values in Valle del Belice dairy sheep because they explain a large part of the genetic potentiality of the animals. The higher values of rank correlation coefficients were between estimated breeding values from selection criteria whose correlations with LL were lower.…”

“…After these edits, in total 6370 lactations from 3483 ewes distributed among 16 flocks were available for analysis. The following variables were used as selection criteria: total milk yield (TMY), corrected milk yield over 186 days of lactation (CMY) (Carta et al, 1998), maximum test-day yield (MTY), lactation length (LL) and milk yield at standard lactation length of hundred days (MYH). Total milk production and milk yield at standard length were estimated using the A4 method adopted according to the international regulations for milk recording in sheep (ICAR, 1992).…”

“…Therefore shorter and longer lactations are adjusted to standard lactation length. For Valle del Belice ewes, lactations are adjusted to 186 days by multiplicative factors as described by Carta et al (1998). The quality of the adjustment procedure depends on the accuracy of milk recording with regard to temporal aspects.…”

Physico-chemical characteristics and acidic profile of PDO Pecorino Romano cheese: Seasonal variation

“…A total of 70 samples of Pecorino Romano cheese were collected and in particular 10 from March, 30 from April, 20 from May and 10 from June productions. Sarda sheep production system depends on natural pasturing, and feed availability is strongly affected by seasonal and annual climatic variations (Carta et al, 1996). With the arrival of summer season, the decline of the quality of pasture might have induced a decrease in de novo synthesis of fatty acids with chain length less than 16 carbon atoms (Chilliard et al, 2001) and might have favored long-chain fatty acids, in particular C18:0 (stearic acid) and C18:1 (oleic acid), which are usually associated with the mobilization of stored fat (Chilliard et al, 2003).…”

Time-to-event analysis of mastitis at first-lactation in Valle del Belice ewes

“…LS i is the fixed effect of the ith lambing season class, where i = 1 when lambing occurred from August to November (conventional); i = 2, from December to March (winter); and i = 3, from April to July (late); TMY j is the fixed effect of the jth class of total milk yield adjusted (TMY adj ) for lactation length (Carta et al, 1998), where the classes were labelled, based on interquartile limits, as 1: TMY adj < 146.9 kg; 2: 146.9 kg ≤ TMY adj < 189.3 kg; 3: 189.3 kg ≤ TMY adj < 240.3 kg; 4 when TMY adj ≥ 240.3 kg; and 0 when TMY adj records were missing; fy k is the random effect of the kth flock by year of lambing subclass, with k = 1, …, 70 (from up to 17 flocks in 6 years of lambing, from 1998 to 2003); and a l is the random effect of the additive genetic component of the lth individual, with l = 1, …, 3114.…”