Effects of controlled feed intake, starting time on feed, and housing system on yearling steer performance

摘要

In a three-year study of the effect of controlled feed intake with different starting times and housing systems, a total of 2,111 yearling steers were started on feed four times a year, in March, June, September, and December. The types of housing consisted of open lots with overhead shelter, open lots without shelter, and lots in a cold confinement building. A high concentrate diet was distributed at ad libitum, 95%, and 90% of ad libitum in each type of housing. Controlling the feed intake of yearling steers resulted overall in a decrease (P\u3c.0001) of ADG with feeding level. Feed efficiencies (FE) were similar among the three levels of feeding. Also, there was no main effect of feeding level on most carcass traits. The starting time on feed had no effect on any of the variables. The type of housing affected all feedlot performance variables as well as hot carcass weight (P\u3c.0001), dressing percentage (P\u3c.0001), and KPH (P\u3c.003), whereas feed efficiency manifested a housing x feeding level interaction (P\u3c.05). There was a starting time x housing interaction for ADG (P\u3c.004) and FE (P\u3c.01). Concerning the economic aspects, restricting feed intake increased days-on-feed (P\u3c.0001) and interest costs (IC; P\u3c.0001), but it did not affect the financial returns over variable costs (RVC) or total costs (RTC). There was a main effect of starting time on feeder purchase costs (FPC; P\u3c.02), total variable costs (TVC; P\u3c.01), total costs (TC; P\u3c.01), and steer sale prices (SSP; P\u3c.05)); but it did not affect the estimated returns. A starting time x feeding level interaction was observed for feed costs (FC; P\u3c.03) and TC (P\u3c.05). The main effect of housing on most variables was indicative of the higher costs of feeding cattle in confinement. However, cattle in confinement also yielded greater (P\u3c.001) SSP resulting in similar RTC among types of housing. The housing x feeding level interaction was significant (P\u3c.04) for TC, whereas the starting time x housing interaction affected FC (P\u3c.01), thus TC (P\u3c.02), and RTC (P\u3c.04). A ten-year estimate of the economic variables showed that RTC decreased (P\u3c.003) with feeding level despite lower (P\u3c.05) TC for restricted-fed steers. There was a main effect of starting time on FPC (P\u3c.0001), TVC (P\u3c.0002), and TC (P\u3c.0002), whereas the type of housing affected (P\u3c.0001) all considered variables, as did the two-way interactions between starting time, housing, and feeding level.