What can dietary enzymes do for heifers?
A group of Korean researchers tracked the influence of beta-mannanase on heifers getting diets with high levels of mannan or more conventional diets. The group examined dry matter intake (DMI), the feed conversion ratio, average daily gain (ADG) and growth rate.
“The objective of this study was thus to investigate the effect of supplementation of β-mannanase in growing heifers fed a diet composed of either a conventional corn-soy based or HMCF [high mannan containing feedstuffs] based concentrate mix,” said the researchers. “A feeding trial using Hanwoo heifers, a dominant beef breed in Korea, was conducted, and growth performance (i.e., daily intake, body weight gain, feed conversion ratio) of the heifers was measured.”
Team members said they found benefits from the feed supplement in both types of diets and to heifer performance.
“Results indicated that supplementation of β-mannanase enhanced growth rate and feed efficiency of Hanwoo heifers regardless of the basal diets,” said the researchers. “Therefore, we conclude that supplementation of β-mannanase can be beneficial to improve the feed utilization in Hanwoo growing heifers.”
Why beta-mannanase?
The group looked at the use of the supplement in heifer diets as a way to help animal producers better use low-cost feed ingredients.
Some of the by-products used in feed contain large amounts of beta-mannan, including palm kernel meal, copra meal and soybean hulls, said the researchers.
But diets with large amounts of mannan can reduce the nutrient intake and water absorption in monogastric animals, they said. Using beta-mannanase can improve results.
Use of the enzyme beta-mannanase has been shown to improve results in chickens and pigs, they said. It also has been used in calves getting a soy-based milk replacer and tested in goat diets.
“No study, however, has been conducted to evaluate the effect of β-mannanase supplementation in growing heifers,” they said. “Moreover, little is known whether β-mannanase supplementation also has beneficial effects in conventional corn-soy based diets.”
Experiment
In the experiment, 40 heifers were given one of four diets for a period of 12 weeks, said the researchers.
The diets included a total mixed ration made from 250g/kg ryegrass and 750 g/kg of a concentrate made from either a corn-soy mix or high mannan containing feedstuffs (HMCF), they said. Both diets either had or did not have supplemental commercially produced beta-mannanase at 1g/kg dry matter basis.
Feed intake and body weights were taken daily, they said. And, interactions between treatment and monthly body weight changes were analyzed.
Results
The use of the beta-mannanase supplement improved ADG by the heifers regardless of basal diet, said the researchers. It improved intake by about 111g/d for the corn-soy diet and 90g/d for the HMCF diet.
“β-mannanase supplementation tended to decrease feed conversion ratio (DMI/ADG) by 1.3 on average,” they said. “The ADG of CS [corn-soy diet] (943 g/d) was significantly greater than that of HMCF (854 g/d).”
But no major differences were seen in dry matter intake, they said. Large changes to initial or final body weights were not noted.
“Analysis of repeated measures with animal as a random variable also indicated monthly BW [body weight] changes of the heifers were significantly different among the treatments; a significant interaction between month and treatment was observed,” said the researchers. “Based on this analysis, the estimated monthly body weight changes of CS, CS_ENZ, HMCF, and HMCF_ENZ were 26.3, 29.0, 23.0, or 25.8 kg/month, respectively.”
Additional research examining dosage of the supplement and the mechanism involved should be conducted, they said.
Source: Livestock Science
Title: Enhancement of daily gain and feed efficiency of growing heifers by dietary supplementation of β-mannanase in Hanwoo (Bos taurus coreanae)
DOI: doi:10.1016/j.livsci.2016.04.001
Authors: Jakyeom Seo, Jeongsoo Park, Junsung Lee, Jae-Hwan Lee, Jung-Jin Lee, Dong Keun Kam, Seongwon Seo,
