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Can producers feed alternative diets to bred cows?
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Can producers feed alternative diets to bred cows?

Winter feeding costs account for the majority of annual operating costs in a cow/calf operation.

While forages are typically a major component of beef cow diets, high prices or limited availability of forages may lead livestock producers to consider alternative feeds.

A study by NDSU’s Hettinger Research Extension Center (HREC) evaluated performance differences between forage-based and grain-based diets in bred cows who were in mid- and late gestation, as well as the offspring’s feedlot performance and carcass composition.

“We’ve been conducting maternal programming work for years now, and every study leads to another question,” said Janna Block, NDSU Extension livestock systems specialist at HREC.

Cows were preg-checked and assigned to dietary treatments based on age and body weight, and nutritional needs were met in both diets.

“The majority of fetal growth happens in the last 60 days, so we were careful to meet nutritional requirements,” she said.

Dietary treatments were initiated around day 94 of gestation, which is at the beginning of mid-gestation – or about six months before calving. Cows were removed from treatments about a month prior to calving.

The first treatment was a limit-fed concentrate, with a mineral package in it. The diet consisted of a small amount of wheat straw, but was mostly corn grain and distillers grains.

“The corn grain was nearly 57 percent of their diet,” she said. “Whenever you are over 50 percent, that is a concentrate diet.”

In this limit-fed diet, cows were fed to meet their nutritional requirements with no additional grazing or forage.

“With a concentrate diet, you can meet the needs of the cow with less feed because it is so energy dense,” she said.

Cows fed a concentrate diet can appear “more hungry” than those cows on a forage-based diet.

“The cows may seem hungry because they are not able to consume as many pounds as they would like to, but they look good and perform well,” Block said. “It may take a few weeks, but the cows will adjust to the different diet.”

Depending on the cost of corn and/or distillers grains, there are times when a producer could save money feeding a concentrate-based diet.

“If corn is priced right and if hay is low quality or not available, a concentrate diet may cost less and make sense nutritionally,” she said.

In a drought year, for example, when grass might be low quality in pastures, resulting in poor hay or no hay, a producer could consider alternative diets, such as corn and distillers grains.

However, feeding a concentrate diet is a management adjustment.

“It is a huge management adjustment to the way producers typically manage their range cows. Ranchers want to feed hay, and it is hard to feed a limited diet, even though it is meeting the nutritional needs,” she said. “Once some adjustments are made, both the ranchers and the cows will do just fine.”

When it is extra cold outside in the winter, producers may need to feed some higher quality forage (if available), or additional concentrate to help generate body heat. 

The second treatment in the study was a forage-based diet containing wheat straw, along with high quality alfalfa hay, a tiny amount of corn silage and a protein supplement with a mineral package.

“The majority of the forage-based diet was wheat straw,” she said.

Intake on the forage-based diet was also controlled so that nutrients supplied were equal among treatments.

The cows on the forage-based diet seemed to be more satisfied or “full” than with the concentrate diet, at least initially.

Block found there were not any statistical differences in cow body condition score throughout the study, however, there was a tendency for increased weight gain for cows consuming the concentrate-based diet. 

“Their nutritional requirements are high during late gestation, and both treatments met requirements,” she said.

HREC scientists also tracked the economics – cost of the feeds and other costs associated with feeding.

They brought the cows home before calving.

“We took good care of the cows. It was a cold winter, but they did have access to windbreaks and kept maintenance requirements met,” she said.

Different types of feeds (forage vs. grain) produce different volatile fatty acids (VFA).  These VFAs are the main products of digestion of feed by bacteria in the rumen, and they provide more than 70 percent of the cow’s energy supply.

“Those different VFAs could perhaps affect the way the metabolism is developing in the calf, and ultimately influence meat quality, as well,” Block said.

Did the dam’s diet affect the development of the offspring in such a way that it would affect feedlot performance?

“We’re interested in following the calves through on feedlot performance and on meat quality, such as carcass weight, ribeye area, backfat and marbling accumulation,” Block said.

The area of fetal programming is still relatively new, although there has been a great deal of research in this area over the past 10-20 years.

“We still don’t know a lot about the different mechanisms that might affect what nutrients flow to the fetus and how this may impact development. It is a complicated process, and we are just on the edge of understanding it,” she said. “Other published studies have shown there may be some differences depending on the dietary energy source.”

Calves from dams in this study were weighed and tagged within 24 hours of birth.

Pairs were managed as a common group through weaning, with no further treatments applied to dams or their offspring.

Following weaning, a subset of 40 calves were fed high grain diets during backgrounding and finishing. 

Although there were some minor differences in fat accumulation based on ultrasound measurements during the finishing phase, there were no differences overall for weight, average daily gain, or feed conversion.

Individual carcass data was collected and carcass quality was evaluated. 

In addition, a trained sensory panel was utilized to evaluate consumer palatability of steaks representing each maternal dietary treatment. 

The consumer panel showed similar scores for tenderness and flavor of steaks. However, steaks from offspring of dams on the concentrate-based diet were perceived as having slightly higher “juiciness” scores. 

Overall, results from this study indicated that the cows’ diets had minimal impacts on their performance and did not influence birth weight, weaning weight, feedlot performance or carcass characteristics of their calves, with only minor impacts on meat quality of the offspring.

“Providing all the nutrient requirements are met for cows, you can feed alternative diets,” she said. “Their offspring should still perform well in the feedlot and on the rail, provided they have a good genetic background.”

The study was recently published in the 2020 North Dakota Beef and Sheep Report, which is available at: https://www.ag.ndsu.edu/publications/livestock/2020-north-dakota-beef-and-sheep-report). 

The Prairie Star Weekly Update

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