Dry Matter Intake of Beef Heifers Fed Diets Supplemented with Progressive Increments of Whey Extract Powder

Whey extract powder (WEP) was evaluated as a beef diet supplement through a 6-wk trial performed at the Lancaster Agricultural Research Station (Lancaster, WI). Seventy-two yearling heifers (initial BW 279 ± 26 kg) were stratified by weight and within 12 strata, 1 heifer was assigned to each of 6 pens. . After 1 wk of basal diet feeding, pens of heifers were randomly assigned to either continue receiving the basal diet or to receive increasing levels of WEP. In wks 2 through 5, 3 pens received increasing amounts of WEP—1, 3, 6, and 9% of diet DM, respectively. In wk 6, all pens were again fed the basal diet and then weighed. Throughout the trial feed bunks were monitored for feed refusals and daily ration allowance was adjusted to ensure that feed offered matched feed consumed. Individual ingredients and diets were sampled twice weekly and were dried at 50°C to quantify DM. Weekly pen DMI were subjected to ANOVA using JMP 13.0.0 (SAS Inst. Inc., Carey, NC). The model included the fixed effect of WEP inclusion rate. Pen was the experimental unit and significance was declared at P ≤ 0.05. Week 1 DM intake (DMI) of basal diet was not different across pens (P = 0.82). Intake of diet supplemented with 1% WEP was not different (P > 0.68) than DMI of basal diet. However, DMI of diet supplemented with 3, 6 and 9% WEP were less (P < 0.01) than basal diet. There was a trend (P < 0.08) for ADG of heifers fed basal diet (1.26 kg/d) to be greater than ADG of heifers receiving WEP (1.13 kg/d) which is consistent with suppressed DMI when fed more than 1% WEP.

Table 1. Daily DMI (kg/hd) of beef heifers fed incremental levels of whey extract powder (WEP)1
Week	Basal2	WEP3		SEM	P-value
1	6.35	6.35		0.02	0.822
2	6.80	6.80		0.02	0.683
3	7.12	7.03		0.02	0.001
4	7.26	6.89		0.05	< 0.001
5	8.30	7.30		0.09	< 0.001
6	8.71	8.07		0.22	0.043
1 Supplied by Agri Processing Services LLC (Carmel, IN). 2 35% corn silage, 50% alfalfa haylage, 12% cracked corn, and 3% trace nutrient supplement (DM basis). 3 All ingredient percentages of the basal diet diluted by WEP on a DM basis at the rate of 0, 1, 3, 6, 9, and 0% in week 1 through 6 respectively