A team of researchers at several universities in Brazil examined the use of chitosan and soybean oil in the diets of lactating dairy cattle. The group published its results in the journal of Livestock Science.
“This study evaluated the combined use of chitosan and soybean oil in dairy cow diets on ruminal fermentation, intake and digestibility, N [nitrogen] balance, productive performance and milk fatty acids profile,” the researchers said.
The researchers found that adding the feed supplement without soybean oil improved animal efficiency and performance, they said. “Chitosan improved animal performance and nutrient utilization efficiency, increasing long chain fatty acid concentration, showing a very promising feed additive in dairy cow diets without fat supplementation,” they added.
“The addition of chitosan in diets containing soybean oil compromised performance, showing negative interaction of chitosan with basal diet components,” they said.
One of the challenges for supporting increasing lactation productivity in dairy cows has been meeting energy requirements, said the researchers. An often studied idea to address the challenge is to use dietary additives to modulate ruminal digestion.
Additives used primarily have antimicrobial traits like ionophore, they said. These have been successful in boosting efficiency of protein and energy utilization.
However, antibiotic use in animal feeds is increasingly less socially acceptable because of residues and the potential for developing strains of bacteria resistant to antibiotics, they said.
Chitosan is a nontoxic, biodegradable biopolymer that has been established uses in medicine and food preservation as it also has antimicrobial activities, said the researchers. It is obtained from chitin – a components in exoskeletons of insects and crustaceans.
Previous research with the feed ingredient found that it inhibits in vitro bio-hydrogenation and bumps unsaturated fatty acid concentration, they said. Other work showed that rumen propionate rose, ammonium fell and it had no effect on intake or total tract digestibility for sheep.
Another method for supporting energy requirements in dairy cattle is to offer feeds with a higher energy density, said the researchers. Lipids can raise the energy density of diets and may alter ruminal fermentation and milk fatty acid profiles.
“We hypothesized that chitosan and lipids association may improve ruminal fermentation, productive performance, energy status and milk fatty acids profile,” they said.
Methods and materials
In the study, 24 in-lactation dairy cows were given one of four diets for 21 day periods, the researchers said. The corn silage, corn and soybean meal diets included two levels of chitosan at 0 or 4g/kg of dry matter and two levels of soybean oil 0 and 33 g/kg of dietary dry matter.
Each feeding period had 14 days for adaption, and seven days for sample collection, they. Samples of feeds, refusals and fecal matter were taken and checked for dry matter (DM), crude protein (CP) ether extract (EE), acid-detergent fiber (ADF), lignin, ash and neutral-detergent fiber (NDF).
Apparent digestibility of nutrients was established, they said. Ruminal liquid was collected on day 20 of each experimental phase and checked for volatile fatty acid levels.
Blood samples were taken on day 15 of each period, daily urine volume was recorded along with milk yield and samples were taken and analyzed, they said. Milk also was checked for fatty acid content.
An interaction effect between dietary soybean oil and chitosan supplementation was seen for DM, CP and NDF, said the researchers.
The researchers found that adding chitosan reduced intake for the diets without additional oil, they said. However, it also increased concentration of polyunsaturated fatty acids in milk, and nitrogen and energy efficiency.
“Chitosan addition in free-fat diets improved feed efficiency, increased milk unsaturated fatty acids concentration and association with soybean oil negatively affect animal performance,” they said.
The supplement did not alter EE intake or digestibility coefficients, but limited dry matter and crude protein digestibility, they said. Combining soybean oil and chitosan increased total serum cholesterol, but did not alter long-chain milk fatty acids.
Additional soybean oil in the diet increased propionate and lowered acetate ruminal molar proportion and decreased the acetate : propionate ratio, the researchers said. It also reduced short and medium milk fatty acid concentration.
Dietary chitosan, with or without soybean oil, did not alter ruminal fermentation variables, they said.
“A significant soybean oil × chitosan interaction effect was observed on net energy intake and efficiency of energy usage,” they said. “Animals fed diets without soybean oil showed decreased net energy intake and increased energy usage efficiency when chitosan was dietary added. However, chitosan decreased energy usage efficiency and had no effect on net energy intake of those animals fed fat supplemented diets.”
Source: Livestock Science
Title: Dietary chitosan improves nitrogen use and feed conversion in diets for mid-lactation dairy cows
Authors: T. Del Valle, P. de Paiva, E. de Jesusb, G. de Almeida, F. Zanferari, A. Costa, I. Bueno, F. Rennó