MR Dally | PubMed Health

PubMed2000

Sexual performance of twin ram lambs and the effect of number and sex of contemporary siblings.

The objectives of this investigation were to determine the degree of correspondence in the sexual performance of twin male sheep and to compare the sexual performance of ram lambs born co-twin to another male (M-M), co-twin to a female (M-F) and as single (S) offspring. Individual ram lambs (N=117), including 13 M-M twin sets, were exposed to four estrous ewes for 30 min at 7-day intervals over a 4-week period at 8 to 9 months of age.Frequencies of ejaculation (serving capacity) and mounts without ejaculation were recorded. M-M males averaged 2.9 ejaculations and 13.1 mounts per test. Individuals within 9 of the 13 M-M twin sets (69%) differed by an average of 0.5 or fewer ejaculations per test. Although variability within M-M twin sets was very low, variability between the 13 M-M twin sets was also low (coefficient of variation=10.6%). Consequently, frequencies of both ejaculation and mounting (without ejaculation) within the 13 twin sets were not correlated (P=0.50 and P=0.10, respectively). When the progeny of individual sires were compared, mounting frequencies were correlated (P<0.02) but not ejaculation rates (P=0.72). M-M, M-F and S ram lambs did not differ for either ejaculation frequency (P=0.26) or mounts without ejaculation (P=0.98). It was concluded that the sexual performance of related individuals is likely to be very similar and that the number and sex of contemporary siblings does not necessarily influence rates of mounting and ejaculation.

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PubMed1998

Early handling increases lamb affinity for humans

Domestic animals that are socialized to humans are often more easily managed and less timid than those that are not. We examined whether increased handling and artificial feeding of domestic sheep, Ovis aries, at an early age would decrease their subsequent timidity towards people. Forty-eight lamb twin sets were divided into four treatment groups for 2 days of treatment at ages 1-3, 3-5, 5-7 or 7-9 days. Treatment lambs were fed milk replacer and were handled four times/day for 5-min periods. Their twins, used as controls, were left with their dams. Two 5-min tests of lamb temperament were conducted at ages 2, 4, 6, 8, 10, 15 and 25 days. Testing consisted of a stationary human encounter, in which lambs' responses to a sitting person were recorded continuously, and a moving human encounter, in which lambs' responses to a person walking at 0.5 m/2 s were recorded by instantaneous scans. Measures included latency to proximity (<2 m) and arm's reach (<1 m) of the person, time spent in proximity and within arm's reach, average distance (m), mean number of human contacts, number of lambs contacting a person and following/approach/avoidance. Treatment lambs showed significantly greater affinity for humans than their twin controls. The 1-3-day treatment group showed the greatest response to treatment, consistently outperforming controls in all of the above measures. These results suggest that 40 min of positive human contact at age 1-3 days reduces lamb timidity to people. Socialization of lambs to humans need not disrupt the primary lamb-dam bond, and it may have positive management as well as welfare implications.\C 1998 The Association for the Study of Animal Behaviour Copyright 1998 The Association for the Study of Animal Behaviour Copyright 1998 The Association for the Study of Animal Behaviour.

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