An international team of researchers in Canada and Iran examined the use of grain types and forage on the growth and development of dairy calves. The group published its research in the Journal of Dairy Science.
“In this study, we tested the hypothesis that providing a diet supplemented with fiber can alleviate the negative effects associated with rapidly degradable starch such as barley grain, which may modify rumen conditions and improve calf performance,” said the researchers. “Further, we assume that increasing ruminal fermentation of starch can improve dairy calves' performance if acidosis is avoided with a proper source of forage in the diet.”
The researchers found that there were not interactions among grain sources, forage provision and starter feed intake, they said. But, there was an improvement in starter feed intake, average daily gain (ADG) and final body weight (BW) for calves getting a diet with corn silage (CS) compared to alfalfa hay (AH), although some of the weight gain might be attributed to increased gut fill.
“During the pre-weaning period, barley diets resulted in greater starter feed intake and ADG in calves,” the researchers said in the study. “Overall, barley grain and CS would be recommended for dairy calves during the pre- and post-weaning periods.”
Why add fiber to calf diets?
Development of the reticulorumen both physically and metabolically is an important part of growth as a calf transitions from pre-ruminant to mature ruminant state, said the researchers. Growth in the pre-weaning stage is a completed process that involves interactions for nutritional components and physiological signals dependent on feeding strategy and management.
Previously variations in fermentable carbohydrates and forage sources used in starter feeds have been tied to changes in performance of dairy calves, they said.
Cereal grains like corn and barley are commonly used to add starch to calf feeds, they said. Although feeding concentrate-based diets to calves may stimulate rumen microbial development, the production of volatile fatty acids (VFS), and start rumen development, the inclusion of forage or high-fiber feed improves rumen “muscularization” and volume.
Types of fermentable carbohydrates may offer different rates of fermentation and alter the pH and short chain fatty acids of the rumen, they said. These alterations may affect starter feed intake, calf growth performance and rumen development.
Corn, for example, ferments slower than barley and longer rates of digestion raise the amount of starch bypassing the rumen, said the researchers. “Differences in starch shape, granule size, and interactions between amylose and surface compounds can alter the rate of enzymatic digestion of corn and barley starches,” they added.
Past feeding trials have found that starter feeds with large amounts of ruminal degradable starch lower nutrient intake and rumen development, they said. But it is not clear how different starter types alter ruminal fermentation and meet calves’ energy requirements.
Adding forage to diets for young calves has been suggested as it can improve starter feed intake, ADG and rumen fermentation, increase rumination and limit behavioral problems, the researchers said. Free-choice options of forage sources for calves boosted both starter feed intake and total dry matter intake (DMI) when compared to non-forage supplementation.
Past work has demonstrated the positive effect of alfalfa hay (AH) on improving starter feed intake when it supplemented finely ground starter feed, said the researchers. But did not have the same reaction when used with textured feed.
“Limited information is available on how changes in the dietary content of ruminal fermentable carbohydrate and source of supplemental dietary fiber might influence the performance of dairy calves during the pre- and post-weaning periods,” they said.
Methods and materials
In the feeding trial, 60 calves were given one of six diets for a period of 63 days, the researchers said. In addition to the trial feed ingredients, the calves received 4L per day of milk through day 49.
The diets included barley grain (BG) without a forage supplement, barley grain with AH supplementation, barley with supplemental corn silage (CS), corn grain (CG) with no supplement, CG with AH and CG with supplemental CS, they said.
“The forage-supplemented calves received a starter feed containing 15% chopped AH (particle size distribution: 1.0 ± 0.2% greater than 18 mm, 26.0 ± 1.9% between 8 and 18 mm, 35.1 ± 0.9% between 1.18 and 8 mm, and 37.8 ± 2.3% less than 1.18 mm and geometric mean particle 2.9 ± 0.1 mm) or CS (particle size distribution: 21.3 ± 1.5% greater than 18 mm, 62.6 ± 2.0% between 8 and 18 mm, 14.6 ± 1.1% between 1.18 and 8 mm, and 1.3 ± 0.58% less than 1.18 mm and geometric mean particle size 12.07 ± 1.98 mm) as a TMR mixed with concentrates throughout the study,” they said. “Corn and barley grain were ground using a hammer mill with 3 mm screen size.”
Feed refused was collected daily as were samples of starter feed and feed offered was recorded, said the researchers. Body weight (BW) was noted weekly and pre-weaning, post-weaning and overall ADG and feed efficiency were determined.
Blood and ruminal fluid samples were collected on day 35, they said. Body measurements were recorded on day 63 and behavioral data was collected through observations throughout the feeding trial.
Results
Calves getting barley feed in place of corn tended to have better starter feed intake overall and during the pre-weaning period, and the overall ADG and pre-weaning ADG tended to be better for calves fed barley rather than corn, said the researchers.
Post-weaning and overall intake of starter feed was higher for calves getting CS-supplemented diets rather than the AH supplement or non-supplemented diets, they said. Pre-weaning, post-weaning and overall ADG were greater for calves getting the CS supplement compared to those getting non-supplemented diets and the CS supplement had better ADG overall and during pre-weaning than the AH calves did.
Feed efficiency was not altered by any of the dietary offerings, they said.
“These results showed no interactions between grain sources and forage provision on calf performance,” said the researchers. “However, the inclusion of CS and barley in starter diets could enhance the growth performance of Holstein calves during the transition from liquid to solid feed.”
Body weights at weaning tended to be heavier for calves getting the CS supplement compared to calves not receiving a supplement, and final body weights was higher for CS calves compared to both AH and non-supplemented calves.
Body length and hearth girth were larger for calves who received barley rather than corn and for those calves getting a forage when compared to those that were not, they said.
Calves receiving the CS diet spent more time ruminating, but calves getting the non-forage supplemented diets spent the most time in non-nutritive oral behaviors, they said. Calves getting the pH diets had higher rumen pH values.
Beta-hydroxybutyrate (BHB) concentration was higher in calves getting CS-supplemented diets compared to those getting either AH or non-forage supplemented diets, they said.
Source: Journal of Dairy Science
Title: Growth performance, feeding behavior, and selected blood metabolites of Holstein dairy calves fed restricted amounts of milk: No interactions between sources of finely ground grain and forage provision
DOI: doi.org/10.3168/jds.2016-11592
Authors: M. Mirzaei, M.Khorvash, G. Ghorbani, M. Kazemi-Bonchenari, M. Ghaffari