
%0 Journal Article
%A Barwick, SA 
%A Kilgour, RJ 
%A Fowler, DG 
%A Wilkins, JF 
%A Harvey, WR 
%T Ram mating performance in Border Leicesters and related breed types. 3. Relationships of ram serving capacity, testis diameter, liveweight, breed and age with flock fertility
%J Australian Journal of Experimental Agriculture
%D 1989/02/01
%V 29
%N 1
%P 17-22
%K 
%R https://doi.org/10.1071/EA9890017
%U https://www.publish.csiro.au/paper/EA9890017 
%X Relationships of ram serving capacity (a measure of serving frequency in pen tests), testis diameter, liveweight, breed and age with flock fertility were studied in 40 rams joined individually for 7 days at high ewe:ram ratios. Rams were either Border Leicester, BLI (a high prolificacy line derived from the Border Leicester and Merino and since released as the Glen Vale breed) or BLI x Border Leicester, and aged either 1.5 or 2.5 years. Joinings were over 2 periods, 2-9 April or 16-23 April. Breed, age, period and interaction effects were also examined. On average (&#177; s.e.), the number of ewes with mating marks in 7 days increased by 2.03 &#177; 0.52 ( P < 0.001) per serve per hour of serving capacity and by 0.40 &#177; 0.18 ( P < 0.05) per kg liveweight. Relationships with pregnancy rate in marked ewes differed between classes of rams. Larger testes were of most benefit when rams were of high serving capacity ( P < 0.0 1 ) or low liveweight (P<0.01). Only serving capacity was related to number of ewes pregnant, the number increasing by an average (&#177; s.e.) of 1.73 &#177; 0.57 ewes per serve per hour (P<0.01). This suggests that a ram's capacity for more frequent service was more important to fertility than was extra testicular tissue. BLI x Border Leicester, BLI, and 2.5-year-old Border Leicester rams impregnated 30-40% more ewes than did 1.5-year-old Border Leicester rams. We estimate that the 1.5-year-old Border Leicester rams could be satisfactorily joined to about 46 ewes and the other rams to about 60 ewes. 
