Performance of primiparous lactating drylot beef cows
on crop residues and processing co-products

V.L. Anderson
Carrington Research Extension Center
North Dakota State University

Introduction
North Dakota has been and will continue to be a cow/calf state. Native range and pastures are occupied by beef cows in relatively uniform east to west distribution across the state (Figure 1), with the exception of the Red River Valley and the northern tier of counties. It is apparent that the arable acres in the state support intensive crop production as well as substantial numbers of beef cows. In addition to traditional grazing, cows subsist on deliberate forage and feed production or through use of cropping system biomass in the form of residues, grain screenings, or processing co-products. Livestock manure contributes substantially to the value of integrating a crop farm with ruminants by reducing fertilizer costs and adding organic matter.

The processing of grains and oilseeds in the state continues to grow with mainstream processors (ADM, Cargill, and the ND Mill and Elevator) and cooperatives or LLC's (Dakota Growers Pasta Company and AgGrow Oils LLC). As a result, the region has an abundance of good quality natural protein sources (sunflower meal, soybean meal, canola meal, crambe meal, safflower meal, linseed meal, wheat midds, corn gluten feed, corn gluten meal, distillers grains, barley malt pellets, edible bean splits, field peas, and alfalfa) with relatively few high energy feeds (corn, barley, and hulless oats). A very high percentage of the co-products are exported to other regions for use in feedlot diets, dairy rations, or manufactured feeds. A much greater proportion of these co-products could be used in the region to supplement low quality forages for increased beef cow-calf production. North Dakota cow numbers could easily double by utilizing cropping system biomass and processing co-products.

To explore the concept of enhancing crop-livestock integration and enterprise diversity, a two year study was initiated in 1996 to compare performance and economics of intensively managed beef cows fed conventional vs alternative feeds. First calf heifers were used in this trial as they are the most challenging to keep growing, rebreed on time, and wean a reasonable calf. This project will attempt to achieve or exceed typical commercial production levels using large amounts of crop residue (small grain straw and corn stover) and supplemental protein sources (wheat midds and corn gluten feed) during lactation, breeding season and up to weaning. If this concept proves successful, alternative feeds can be used in balanced and palatable rations in virtually all phases of beef cow/calf production. This paper summarizes two year's data from post-partum to weaning.

Materials and Methods
After calving in the spring of 1996 and 1997, first calf heifers and their calves were allotted to a control treatment or an alternative feeds treatment (Table 1). Control diets used chopped alfalfa hay and corn silage as the primary ingredients. The alternative diet used small grain straw and wheat middlings as the primary ingredient. Wheat middlings, procured from the Dakota Growers Pasta Company, Carrington, ND consist of the bran, germ and shorts remaining after milling hard wheat for flour or durum for semolina. Dietary treatments were the same both years of the study.

Red Angus x Limousin and reciprocal cross cow/calf pairs were randomly allotted to treatments and housed in two adjacent pens. Each totally mixed ration was fed once daily in fenceline feedbunks. The fixed rations were formulated based on NRC Nutrient Requirements for Beef Cattle (1984) for cows producing 15 pounds of milk. Calves were allowed access to creep feed from approximately June 1 to weaning in late September. A concurrent creep feeding trial was conducted after breeding season with the 30 pairs allotted to four pens of 7 or 8 pairs respectively. Wheat midds were the primary creep feed ingredient.

Cows and calves were weighed at the start of the trial in early May, at the end of breeding season in late July, and at weaning in late September. Cow condition scores were assigned at the same time. One pair was removed in each treatment early in the study in 1996 due to calf health problems unrelated to the study. Natural service sires were penned with the cows on June 13 and removed on August 2 for a 50 day breeding season. Bulls in both treatment groups performed normally. Pregnancy diagnosis was determined by palpation on November 7.

Results and Discussion
Cow weight change pattern was similar for both treatment groups (P>.10) during the trial (Table 2), losing 5 to 17 pounds per head during early lactation and breeding season. Modest gains were observed in both treatments after breeding season from 5 to 23 pounds per head.

Condition scores (CS) at the start of the trial were similar (5.55 and 5.51 on a 9 point scale) with the alternative diet cows tending to improve over the control cows by weaning. Control cows CS decreased .39 over the 137 day trial while alternative cow CS decreased only .13. Conception rate was 93% for control and 87% for alternative feeds cows.

Calf performance on both treatments was similar (P>.10) suggesting milk production was not altered by diet. Overall gains averaged 2.24 for control calves and 2.32 for alternative feeds calves.

Results for cow and calf performance reinforce what other drylot trials with lactating cows have suggested, that beef cows perform to their genetic potential on a wide variety of feedstuffs provided the ration is palatable and balanced to the cows' needs. More research is needed on reproduction with larger numbers of animals.

Feed costs appear to be similar for both treatment groups. Locally grown feeds that can be procured at minimal costs may contribute to cheaper cow diets, but correct formulation and ration presentation are required to minimize waste and contain costs. Considering all the cropping system residues and processing co-products now available, North Dakota beef cow numbers could double without influencing range land use.

Feeding cows in drylot is viable for commercial beef production as it reduces land costs for grazing, provides a market for cropping system products not otherwise salable, and allows herds to be maintained during drought. The need for frequent feeding and management may be the greatest detractor from a drylot beef cow enterprise. This study documents the successful biology and economy of lactating drylot beef cows.

Table 1. Rations formulations and ingredient analysis for supporting intensively managed first calf heifers

         
Table 2. Performance of intensively managed first calf heifers on conventional vs alternative feeds during breeding season and late summer lactation.

    
Table 3. Performance of nursing calves from first calf heifers fed conventional vs alternative feeds during lactation.

^a Based on feed costs of $20/ton for corn silage, $60/ton for alfalfa, $25/ton for straw,
$60/ton for midds, and $300/ton for mineral/salt.
 

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