Alfalfa hay and wet corn gluten feed levels in steam-flaked corn finishing diets

A 153-day finishing experiment was conducted using 631 heifers to determine optimum alfalfa hay and wet corn gluten feed (WCGF) combinations in steam-flaked, corn-based diets. Diets contained either 2 or 6% alfalfa hay and 25, 35, or 45% WCGF (dry basis). Performance was similar (P>0.16) for cattle fed 2 or 6% alfalfa hay. Gain efficiencies (P<0.05) and fat thickness (P<0.10) declined linearly with increasing amounts of WCGF. For heifers fed 2% alfalfa hay, ribeye area increased with increasing dietary WCGF. However for heifers fed 6% alfalfa hay, ribeye area decreased with increasing dietary WCGF. Liver abscesses were lowest for heifers fed 35% WCGF. Alfalfa hay fed at 2% of diet dry matter is sufficient for steam-flaked corn diets containing 25, 35 or 45% WCGF.


Introduction
Wet corn gluten feed (WCGF) has been incorporated into many feedlot diets in the Northern plains, usually as an energy replacement for grain, and has effectively replaced 30% of steam-flaked corn in finishing diets.However, a large fraction of WCGF is fermentable fiber.Due to their cost per unit of energy and potential to shrink, roughages such as alfalfa hay are burdensome in finishing diets.We hypothesized that WCGF could be utilized as both an energy and roughage source to replace a portion of both alfalfa hay and steam-flaked corn.

Experimental Procedures
Six hundred thirty-one crossbred heifers weighing 626 lb were used in a 153-day finishing experiment.
Heifers were randomly allocated to pens and stratified by weight to six treatments (2 pens per diet, 48 to 58 heifers per pen).The steam-flaked corn-based diets consisted of 2 or 6% alfalfa hay and either 25, 35, or 45% WCGF (dry basis) in a 2 × 3 factorial arrangement of treatments.Diet compositions are shown in Table 1.
Heifers were implanted with Synovex ® C on day 1 and were adapted to the final finishing diets within 21 days.Cattle were offered ad libitum access to diets once daily.Final finishing diets provided 300 mg Rumensin ® , 90 mg T ylosin ® , and 0.5 mg MGA ® per heifer daily.On day 56 heifers were reimplanted with Synovex ® Plus.Unconsumed feed was collected, weighed, analyzed for dry matter content, and subtracted from the original feed offered to determine actual feed intakes.
Average daily gain and gain efficiencies were calculated using final weights estimated as hot carcass weight divided by a common dressing percentage (63.3%).

Results and Discussion
Feeding performance and carcass characteristics are summarized in Table 2. Dry matter intake, average daily gain and gain efficiencies were similar (P>0.16) for cattle fed 2 or 6% alfalfa hay, which suggest that feeding 2% alfalfa hay is sufficient roughage for cattle fed these diets.Dry matter intake tended to increase (P=0.19) as the level of WCGF increased; however, average daily gain was not different (P>0.70).This resulted in poorer (P<0.05)feed efficiencies as dietary WCGF increased.We observed an interaction (P<0.10) between levels of alfalfa hay and levels of WCGF for ribeye area.For heifers fed 2% alfalfa hay, ribeye area increased with increasing WCGF.However for heifers fed 6% alfalfa hay, ribeye area decreased with increasing WCGF.Fat thick-ness decreased linearly (P<0.10) as the level of WCGF increased, suggesting a decline in dietary energy with additional WCGF.Although the occurrence of liver abscesses was low (averaging 2.7%), it was lowest when 35% WCGF was fed, implying that a more suitable rumen environment was maintained.
Heifer performance was not affected by reducing alfalfa hay levels to 2% of diet dry matter.Gains were less efficient and carcasses were leaner with increasing levels of WCGF.Alfalfa hay and wet corn gluten feed levels created an interaction for ribeye area.