Relationship between mammary morphology traits and milk yield of Sicilo-Sarde dairy sheep in Tunisia

Sicilo-Sarde is a local breed from northern Tunisia resulting from crossing Sarda and Comisana dairy sheep and is traditionally used for cheese production after lamb weaning. A sample of 52 adult Sicilo-Sarde lactating ewes was used for studying their udder morphological traits and milk yield potential during weeks 4-8 (milking-suckling period) and 10 (milking period) of lactation. Daily milk yield was estimated on a daily basis by using the double oxytocin injection method 4h after machine-milking at d 30 and 45. Udder and teat morphology were also measured at d 45 of lactation. Cisternal area (by ultrasonography) and udder compartments (cisternal and alveolar milk) were evaluated 8h after milking by using atosiban and oxytocin on d 72 of lactation. Milk yield averaged 0.56±0.10L/d and ewes had small (volume, 496±28mL) and healthy udders (CMT, <1), with medium sized teats (length, 18.5±4.9mm; diameter, 10.0±2.0mm) attached at 45±10° A drop in milk production (49%) was found in the transition from suckling (day 30) to milking (week 10). Udder cisterns were multilocular and small sized (half udder area, 11.6±4.5cm2), although cisternal milk accounted for 54% of the total milk in the udder. Correlation between cisternal milk and cisternal area was moderate (R2=0.48; P<0.05). Lag time and total milking time were 1.9±0.1 and 31±5s, respectively. In conclusion, the Sicilo-Sarde ewes evaluated showed medium sized cisterns and teats which were morphologically adequate for machine milking, although milk production needs to be improved. © 2010 Elsevier B.V.