Growth and External Characteristics of Jerseys and Red Sindhi-Jersey Crossbred Females1

Abstract

Data from three stations are presented on comparative body weights, body dimensions and the external surface area of purebred Jerseys and various combinations of Red Sindhis and Jerseys. In general the crosses gained faster than Jerseys up to 12 months of age but only the F₁ and ⅝ Jersey crosses remained larger at 18 months and first lactation. All crosses having 75% or less Sindhi inheritance showed some degree of heterosis for weight gain up to 6 months but the F₁ groups were the only ones which consistently exceeded the higher parent. Due to variation in response to the environment and the numbers involved, the degree of heterosis in the other combinations was not as evident. The trend of skeletal growth was very similar to that for weight in that the crosses tended to excel the Jerseys at the earlier ages but very little of the advantage carried through to the first lactation. There were indications of heterosis in skeletal growth but it was not as pronounced as for weight. Crossing of the two breeds appeared to have the greatest effect on body length, size of head, slope of rump and fleshing. As little as 25% Sindhi inheritance had a distinct effect on these measurements. Indications were that crossing the breeds had a small effect on total body surface area. It is evident that although the Sindhi had a marked effect on certain phenotypic characteristics in the crosses; namely, the dewlap, navel fold, hump, size of ears and head, that would give the appearance of greater surface area, these were largely offset by a more compact body. Copyright © . .