Comparison of Corn Versus Soyhulls as a Source of Energy In Lactating Beef Cow Diets

T.A. Baumann¹, G.P. Lardy¹, W.W. Dvorak¹, and V.L. Anderson ²

¹ NDSU Department of Animal and Range Sciences; ²NDSU Carrington Research Center

Introduction

Supplementing lactating cows is necessary when forage production is not adequate in either quantity or quality to meet the nutrient requirements of lactation. Low quality forages such as winter native pastures, crop residues, and CRP hay often do not provide enough crude protein or energy to adequately maintain cow body weight and body condition score during early lactation. Research by Fleck et al. (1987) and Ovenell (1991) has shown that feeding the proper amounts and type of supplements (those low in starch) improves utilization of low quality forages. Feeding grains with low quality forages may have a negative effect on the digestion of the forage. Soyhulls, a soybean by-product high in digestible fiber, should increase energy intake without the adverse effects normally observed when high-starch feedstuffs are used to supplement low-quality forages (Marston et al., 1993). Determining proper supplement practices is necessary to maintain optimum cattle performance. The cost of supplementing lactating cows may be reduced by feeding byproducts such as soyhulls instead of a cereal grain like corn. However, for energy supplementation to be effective, ruminal degradable intake protein requirements must be met. Therefore, this study evaluated the use of soyhulls versus corn with or without supplemental degradable intake protein in the diets of lactating beef cows.

Procedures

The study utilized 78 cow-calf pairs in a completely randomized design (initial BW 1346±7.5 and 200±3.3 lb for cows and calves, respectively). A basal diet (Table 1) consisting of 75 percent grass hay (11.5% CP, 65.9% NDF, 40.1% ADF; DM basis) and 25% wheat straw (7.4% CP, 75.9% NDF, 50.2% ADF) was fed from May 16 (43±10 d post-partum) to September 6. Pairs were confined in drylot located at the Carrington Research Extension Center with nine to ten pairs per pen. Animals were stratified by calving date and BW and assigned randomly to treatment. Supplemental treatments were 10.5 lbs. dry rolled corn (C), 11.7 lb soyhulls (SH), 8.1 lbs. dry rolled corn plus 3.40 lbs. sunflower meal (C+P), and 9.9 lbs. SH plus 2.33 lbs. sunflower meal (SH+P). Diets were reformulated to meet lower energy requirement of late lactation on July 25 (Table 2). Animals were weighed and cow’s body condition scored every four weeks during the trial. Prior to the start of the trial, five cows from each treatment were chosen randomly for milk sample analysis. Each teat was stripped prior to obtaining a milk sample. Milk yield from cows was determined by the weigh-suckle-weigh method. Calves were allowed to suckle their dams after a three hour separation period. Calves were then separated from their dams for eight hours. Calves were weighed, allowed to suckle to completion, and weighed to determine milk production.

Table 1. Early lactation diet composition percent (dry matter basis).

	Treatment^a
	Corn	Corn/protein	SH	SF/protein
Hay	49	48	47	47
Wheat Straw	16	16	16	16
Corn	34	26	0	0
SH	0	0	37	31
SF meal	0	11	0	7
DMI, lb	30.5	31.5	31.7	32.2
Formulated, Diet CP, %	8.0	11.1	8.9	10.8

^aSH = Soyhulls, SF = Sunflower meal.

Table 2. Late lactation diet composition percent (dry matter basis).

	Treatment^a
	Corn	Corn/protein	SH	SH/protein
Hay	59	57	58	57
Wheat Straw	19	19	19	18
Corn	22	15	0	0
SH	0	0	24	18
SF meal	0	9	0	7
DMI, lb	27.0	27.9	27.7	28.2
Formulated, Diet CP, %	7.7	10.3	8.2	10.2

^aSH = Soyhulls, SF = Sunflower meal.

Results

Energy source and addition of protein had no effect (P > 0.16) on cow BW, BCS, milk yield, or calf BW. During the study, cow BW decreased (P < 0.001) from 1346 to 1288 7.5 lb; BCS decreased (P < 0.001) from 5.58 on d 1 to 5.01 0.05 on d 112, and daily calf milk intake declined (P < 0.001) from 28.9 lb on d 28 to 17.0 2.4 lb on d 112. Calf BW increased (P < 0.001) from 200 to 483 3.3 lb during the 112 d trial (Table 3). Contrasts for supplement type and protein addition were not significant for cow BW (P = 0.16 and 0.62, for supplement type and protein addition, respectively), BCS (P = 0.29, 0.20), milk yield (P = 0.87 and 0.48), and calf BW (P = 0.23 and 0.41; Table 4).

Table 3. Effect of day on body weight, body condition score, milk yield and calf body weight in cows consuming medium quality forage diets.

	Day
Item	1	28	56	84	112	SE	P-value
Cow BW, lb	1346	1347	1329	1293	1288	7.5	< 0.001
BCS	5.58	5.73	5.54	5.40	5.01	0.05	< 0.001
Milk, lb	---	28.9	23.8	19.4	17.0	2.4	< 0.001
Calf BW, lb	200	266	329	412	483	3.3	< 0.001

Table 4. Effect of supplement source and protein addition on body weight, body condition score, milk yield and calf body weight in cows consuming medium quality forage diets.

	Supplement		Protein			Contrast^a
Item	Corn	Soyhulls	(+)	(-)	SE	1	2
Cow BW, lb
Initial	1342	1350	1343	1349	6.0	0.37	0.54
Final	1279	1296	1278	1297	18.9	0.54	0.50
BCS
Initial	5.53	5.63	5.53	5.63	0.07	0.35	0.35
Final	4.95	5.08	5.00	5.03	0.14	0.54	0.90
Milk, lb	22.5	21.8	20.7	23.8	2.9	0.87	0.48
Calf BW, lb
Initial	205	196	201	199	14.2	0.67	0.89
Final	471	495	492	475	9.2	0.12	0.25

^aContrasts for treatment effects within initial or final period. 1 = Corn vs. soyhulls; 2 = with protein vs. without protein.

Discussion

In the current study, cow BW and BCS decreased over time for all treatments, but no differences occurred among treatments. Decrease in BW and BCS may be expected as requirements for peak lactation may not be met with diet sources. All treatments were formulated to be isocaloric. High-energy supplements frequently contain cereal grains that are high in starch (Hibberd et al., 1982). Cereal grain supplements decrease forage digestibility and intake, resulting in no improvements in the nutritional status of cows (Chase and Hibberd, 1987, Martin and Hibberd, 1990). Since no difference in BW and BCS was noted, both supplements had similar effects on forage digestion.

The addition of protein did not increase performance over the non-supplemented treatments. This indicates that the forage-based diet (forage plus corn or SH) supplied adequate protein to meet the lactation requirements of these animals, therefore, milk yields were not affected.

Conclusion

In conclusion, no differences due to supplement type or protein addition were noted for BW, BCS, milk yield, and calf BW. Therefore, corn or SH are suitable as an energy supplement for the quality of forage utilized in this trial. Addition of supplemental protein did not improve cow or calf performance in this trial.

Implications

The use of soyhulls instead of corn as a supplement source for lactating beef cows did not effect milk production, cow body condition score, or calf weaning weights. The addition of sunflower meal as a protein source also had no effect. Soyhulls may be used for supplementation of lactating beef cows when cost effective.

Literature Cited

Chase, C.C., Jr. And C.A. Hibberd. 1987. Utilization of low-quality native grass hay by beef cow fed increasing quantities of corn grain. J. Anim. Sci. 65:557.

Fleck, A. T., K. S. Lusby, F. N. Owens and F. T. McCollum. 1987. Effects of corn gluten feed on forage intake, digestibility and ruminal parameters of cattle fed native grass hay. J. Anim. Sci. 66:750

Hibberd, C. A., D. G. Wagner, R. L. Schemm, E. D. Mitchell, Jr., R. L. Hintz and D. E. Weibel. 1982. Nutritive characteristics of different varieties of sorghum and corn grains. J. Anim. Sci. 55:665.

Marston, T. T., K. S. Lusby, and R. P. Wettemann. 1993. The effects of energy and protein supplements on spring-calving cows. Okla. Ag. Exp. Station.

Martin, S. K. and C. A. Hibberd. 1990. Intake and digestibility of low-quality native grass hay by beef cows supplemented with graded levels of soybean hulls. J. Anim. Sci. 68:4319-4325.

Ovenell, K. H., K. S. Lusby, G. W. Horn, and R. W. McNew. 1991. Effects of lactational status on forage intake, digestibility, and particulate passage rate of beef cow supplemented with soybean meal, wheat middlings, and corn and soybean meal. J. Anim. Sci. 69:2617-2623.