Influence of breed, birth date, age and body weight on linear body measurements of growing rams maintained in a controlled environment.
Heart girth, body length, leg length, metacarpal circumference, withers height and hook width of 233 growing rams of 3 synthetic strains were measured. Strain 1 was developed from the Suffolk, Ile-de-France and Border Leicester (BL) breeds, with minor contributions from the Lincoln Longwool, North Country Cheviot (NCC), Shropshire, Southdown, Romnelet and Corriedale breeds. Strain 2 was developed from the Finnish Landrace (FL), Suffolk and Shropshire breeds, strain 3 was developed from the FL, East Friesian, Dorset Horn, BL, NCC, Shropshire, Suffolk, Romnelet and Corriedale breeds. Also, sheep of the Suffolk and Finnsheep [Finnish Landrace, FL] breeds were measured at 6, 8 and 10 months of age. Thereafter, subsequent measurements were taken at 11-13, 18-21 and 23-25 months of age. Breed, birth date, age of ram and body weight had significant effects on linear body measurements, whereas age of dam did not. Significant effects of litter size on heart girth and body length were observed at 6 and 8 months of age resp. All linear body measurements increased from 6 to 21 months of age, whereas body length, withers height and hook width continued to increase to 25 months. Rams of strain 1 were generally similar to the Suffolk rams in all body measurements, except for heart girth, which was significantly larger than in Suffolk rams. The FL rams had smaller heart girth, body length, metacarpal circumference and hook width than the 3 synthetic strains and Suffolk rams, whereas leg length and withers height of the FL and Suffolk rams were similar. Rams of strains 2 and 3 were similar in body measurements, and did not differ from strain 1 and Suffolk rams with respect to heart girth, body length, withers height and hook width. However, Suffolk rams had a larger metacarpal circumference and a shorter leg length than rams of strains 2 and 3. Birth period had a significant effect on heart girth, body length, leg length and metacarpal circumference, but no consistent trend with age of ram was apparent. Linear body measurements were positively correlated with each other and with body weight; however, the relationship varied as rams progressed in age. The importance of breed, birth date, age of ram and body weight on body measurements and the requirements for appropriate adjustments is emphasised.