In this experiment, grazing and nursing behavior of approximately 30 cow/calf pairs was examined in two years. Sires of the Polled Hereford x Angus cows had been selected for above (+) or below (-) average expected progeny difference for yearling weight and maternal weaning weight. Calves were sired by Angus bulls of United States (US) or New Zealand (NZ) origin. Observations from dawn to dusk were conducted on five days each year, spaced throughout lactation. All nursing episodes were recorded, and every ten minutes it was noted whether each cow and calf was or was not grazing. Periods of maximum grazing activity were early in the morning and late in the afternoon. The growth genotype of the cow did not affect her grazing time. Calves of maternal (+) cows grazed longer than calves of maternal (-) cows (P< 0.10), and their grazing time was not affected by the growth genotype of their dams. In year 1, US-sired calves spent 3% more time grazing than NZ-sired calves; whereas in year 2, NZ-sired calves grazed 4% longer than US-sired calves (interaction P <.10). Also in year 1, NZ-sired calves tended to graze during several intervals of time while US-sired calves tended to graze in longer continuous bouts. This tendency was reversed during the second year (interaction P<.10). As the grazing season progressed, time spent by calves grazing increased from < 20% to approximately 60%. Cows with (+) genetic merit for maternal weaning weight were nursed a similar number of times per day as cows with (-) genetic merit. Sire origin likewise did not affect nursing behavior. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/44911 |
| Date | 29 September 2009 |
| Creators | Ngassa, Tchatchoua |
| Contributors | Animal Science |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | viii, 71 leaves, BTD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 26826236, LD5655.V855_1992.N487.pdf |
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