An international team of researchers from the US, Canada and Iran examined the influence of calf starter feed form on feed intake, rumen development, nutrient digestibility and growth. The team of researchers published their results in the journal of Animal Feed Science and Technology.
“The present study was designed to elucidate the effects of feeding a ground starter feed plus 10% chopped AH [alfalfa hay] compared with ground, textured, or pelleted diets on growth performance, structural growth, and rumen fermentation of dairy calves,” the researchers said. “Furthermore, macroscopic and microscopic observations were used to determine the effect of starter feed physical form on rumen development.”
The researchers found that there was a link between diet form and calf intake, growth and rumen development, they said.
“When calves were not bedded on straw, greater intakes and ADG [average daily gain] were achieved with a ground starter feed supplemented with 10% AH compared with ground, textured, or pelleted starters without AH supplementation,” the researchers said. “Performance and rumen development measures collectively showed improved performance by the Ground + AH group relative to other groups.”
Why feed format?
Development of the reticulorumen, both physically and metabolically, plays a part in the transition from pre-ruminant to ruminant and may improve calf health, said the researchers. The physical form of a starter feed and its processing may alter palatability and intake by dairy calves.
Pelleting can improve palatability and limit ingredient segregation in starter feeds, and it may alter rumen fermentation as it has smaller particles, which can reduce digestion and hinder feed intake, they said. Earlier research found that both intake and nutrient digestibility was reduced in calves getting a pelleted starter when compared to a feed in a coarse mash form.
Additionally, it has been found that a textured diet can lead to improved performance compared to use of a finely ground starter feed, they said. Previous research showed that a textured feed can improve intake and ADG compared to use of a pelleted or ground feed, but textured feed also is usually more expensive.
However, using a ground starter feed with a supplement of alfalfa hay may promote normal development of the rumen epithelium without the need for a textured or pelleted starter feed, they said. This practice also may reduce costs for dairy producers.
In the feeding trial, 52, 3-day old dairy calves were given one of four dietary measures for a period of 70 days, the researchers said.
The four feed types tested included a ground starter feed, a textured starter feed that included steam flaked corn and barley, a pelleted starter feed and a ground starter feed with 10% chopped alfalfa, they said. Diets also included 6 liters/day of milk from day 3 to 47 and 2.5 liters/day from day 47 to 49 with weaning occurring on day 50.
Intake of starter feed and feed refused were recorded daily and body weights (BW) were noted every 10 days, they said. ADG and feed efficiency were determined.
Samples of starter feeds, refusals and fecal matter were collected and analyzed, they said. Samples were checked for crude protein (CP), ether extract, calcium, phosphorus, non-detergent fiber (NDF), sodium sulfite and total tract nutrient digestibility.
Calves were measured on days 50 and 70 for body length, withers height, body barrel, heart girth, hip height and hip width, the researchers said. They were also monitored for behavior.
Rumen fluid was sampled on days 35 and 70, they said. A selection of digestive tracts were collected at the end of the study.
Overall there was link between the type of starter feed and growth and rumen development in calves, the researchers said.
“Compared with ground, textured, and pelleted starter feed, ground starter feed supplemented with 10% alfalfa hay benefitted performance and rumen pH, and positively influenced both the macroscopic and microscopic morphology of the rumen wall,” they said.
Calves receiving the ground feed with hay had better intake of starter feed, weaning BW, final BW and ADG when compared to calves getting other diets, they said. Calves getting ground or textured feeds had better intake of starter than those getting the pelleted feed.
However, feed efficiency was similar for all groups of calves regardless of diet, they said. And no differences were found for hip height, body length, withers height, hip width or heart girth.
Apparent digestibility of dry matter, organic matter and CP were better for calves getting diet types other than the ground diet, said the researchers. However, calves getting ground feed with hay spent more time eating and ruminating than those getting other types of feeds.
Calves getting the ground diet with hay had a higher ruminal pH and more ruminal ammoniacal nitrogen (NH3-N), but reduced volatile fatty acids (VFA) compared to those getting the pelleted diets, they said. The diet was also found to promote rumen development and growth compared to the pelleted or ground feeds alone.
Source: Animal Feed Science and Technology
Title: Growth performance, nutrient digestibility, ruminal fermentation, and rumen development of calves during transition from liquid to solid feed: Effects of physical form of starter feed and forage provision
Authors: A. Pazoki, G. Ghorbani, S. Kargar, A. Sadeghi-Sefidmazgi, M. Ghaffari, J. Drackley