EFFECTS OF BIRTH TYPE, AGE OF DAM, ENTRY WEIGHT AND PRESTATION GAIN ON TEST STATION RESULTS OF RAM LAMBS

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Abstract
Records on 1820 Suffolk ram lambs from seven test stations were studied to determine the effect of birth type of lamb, age of dam, entry weight and prestation gain on test results at Canadian Record of Performance (ROP) Test Stations. Rams born as singles were heavier (P < 0.05) at station entry and gained more (P < 0.05) from birth to station entry (prestation gain) than rams born as twins or triplets, whereas twins and triplets were similar in this respect (P > 0.05). Weight on test and gain during adjustment period of rams born as singles, twins or triplets reflected these differences. Daily gain of rams on test was not influenced by type of birth. Age of dam did not affect entry weight, prestation gain, daily gain in the adjustment period, on-test weight or daily gain. The relationship between entry weight (EW) and average daily gain on test (ADG) was curvilinear and is described by the equation: ADG = 0.3244 + 0.0128 EW - 0.00021 EW2 (r = 0.13, SE = 0.068, P < 0.001). The 95% confidence limits of entry weight for maximum ADG were 16.2-39.8 kg. The relationship between prestation gain (PG) and ADG was also curvilinear ADG = 0.3529 + 0.6022 PG - 0.5427 PG2, (r = 0.11, SE = 0.068, P < 0.001). The 95% confidence limits of prestation gain for maximum ADG were 0.27-0.71 kg d-1. Ram lambs with entry weights and prestation gain outside the 95% confidence limits had lower ADG. Test station results of ram lambs were not affected by birth type of lamb, age of dam, entry weights between 16 and 40 kg and prestation gains between 0.27 and 0.71 kg d-1.

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