Performance and Metabolism of Dairy Cows Fed Bean Seeds (Vicia faba) with Different Levels of Anti-Nutritional Substances

The aim of this study was to determine the effect of selected bean cultivars with different levels of anti-nutritional substances on performance and metabolism of dairy cows. In the current twelve-week-long study, 32 dairy cows at 3 to 6 weeks after parturition were divided into four groups. Diets were balanced to have an analogical content of crude protein and energy. Experimental groups (MI, ME, MET) were mixed to the milking concentrate consisting of 20% bean seeds (MI MISTRAL cultivar with a low content of anti-nutritional substances; ME MERKUR cultivar with high content of anti-nutritional substances; MET MERKUR cultivar with technologically reduced the amount of anti-nutritional substances). Clinical evaluation of dairy cows’ health and feed intake showed no negative effect of the bean supplementations. Energy, nitrogen and mineral metabolisms were not impaired either. No significant differences were found between groups in milk performance (daily milk yield, protein and lactose production) during the study. On the basis of these results, the bean can be used in 20% in the milking concentrate of dairy cattle. Health risks associated with anti-nutritional content of the native bean are not significant for high-producing dairy cattle. Bean, metabolism, milk performance, reproduction, anti-nutritional substances Bean seeds (Faba vulgaris Moench., syn. Vicia faba L.) are important sources of proteins used in diets of farm animals. Globally, the bean and lupin are grown on the smallest acreage among all pulses. In our climate, beans are used mainly as a fodder crop. Bean seeds contain on average 30–34% crude protein (CP), 6–7% fibre, 47–51% N-free extract (NFE), 33– 40% starch, 0.9% ether extract (EE), and 3.3–3.7% ash. When compared to soybean, bean has lower lysine and arginine values (17.6 g·kg-1 vs. 25.5 g·kg-1, respectively) and a low content of sulphur amino acids (6 g·kg-1 vs. 13.3 g·kg-1 of feed ration’s dry matter) (Cerioli et al. 1998). Protein and starch degradability of the bean can be influenced by technological treatment. Aleksić et al. (1999a) tested the protein degradability of faba beans in the rumen of cannulated lactating cows. The rate of protein degradability was determined as more than 47%. Aguilera et al. (1992) reported lower degradability of protein by heat treatment (120 °C for 30 min) of bean compared to untreated bean. Benchaar et al. (1992) studied the effect of extruded bean, representing 45% of the feeding ration protein content, on digestion of nitrogenous substances and starch in the rumen and small intestine. The percentage of degradable protein in the intestine was 38% in extruded bean as compared with 33.5% in untreated bean. Cros et al. (1991) came to a similar conclusion and they found that adding extruded bean seeds to diet increases intestinal availability of proteins from the feed. The effect of bean heat treatment on amino acid composition was studied by Cros et al. (1992). Dairy cows fed heat-treated beans showed better utilization of amino acids in the small intestine. Extrusion did not affect amino acids composition. Similarly Yu et al. (2000) stated that extrusion of bean at 136 °C for 15 min yielded the highest values of actually digestible protein in the intestine and, at the same time, it maintained a sufficient amount of degradable protein for microbial proteosynthesis. Martinez et al. (2004) describe better utilization of protein in ruminants fed protein concentrates (bean meal) with ACTA VET. BRNO 2009, 78: 57–66; doi:10.2754/avb200978010057 Address for correspondence: Doc. MVDr. Alena Pechová, CSc., Dipl. ECBHM Ruminant clinic, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences Brno, Palackého 1-3, 612 42 Brno, Czech Republic Phone: +420 54156 2408 E-mail: [email protected] http://www.vfu.cz/acta-vet/actavet.htm tannins added. The rumen hydrolysis and deamination of protein was significantly lower in cows fed protein concentrates with tannins. The protein utilization was enhanced and no change in starch digestion after treatment of tannins was found. The effective starch degradability of faba bean grains in the rumen of lactating cows was determined to be more than 58% (Aleksic et al. 1999b). Benchaar et al. (1992) studied the effect of heat treatment of bean (extrusion) on the utilization of starches in the small intestine of dairy cows. Feeding extruded beans improved ruminal digestibility of starches compared to untreated beans (72% vs. 58%) and their subsequent utilization in the small intestine (0.98 vs. 1.61 kg·day-1). Other authors reported a decrease in starch digestibility in the rumen after feeding extruded beans, though it increased again when feeding a mixture of various pulses (Goelema et al. 1998). The anti-nutritional substances present in the bean can negatively influence the digestion of individual nutrient and also the health state and performance of the high-producing dairy cows. The bean contains the following anti-nutritional substances: trypsin inhibitors, lectins (phytohaemaglutinins), tannins, flatulent oligosaccharides, gallic acid and other substances from the phenolic group, and glycosides such as vicine and convicine (Dvořák et al. 2006). The bean has a lower content of trypsin inhibitors than the soybean (0.97 mg·g-1 vs. 18 mg·g-1 respectively), shows no urease activity, which reaches 2.9 mg N·g-1 in the soybean, but contains more tannins (3.1 mg·kg-1 vs. 0 mg·kg-1) (Cerioli et al. 1998). The aim of our experiment was to evaluate the influence of the content of anti-nutritional substances in the bean on the metabolism and performance of the high producing dairy cows. We used two different bean cultivars: Mistral with a low and Merkur with a high content of antinutritional substances. We also tested the Merkur cultivar whose content of antinutritional substances was reduced technologically using a new method of technological treatment developed for this reason. Materials and Methods The experiment was performed in a four-row tie-up barn (located in eastern Bohemia) in 2006. Thirty-two dairy cows were used in the study. They were at the beginning of their lactation period, i.e. 3 to 6 weeks after parturition. They were divided into 3 experimental groups and 1 control group on the principle of analogous tetrads according to breed, order of lactation, performance in the last lactation and the current performance. All dairy cows were fed the same basic diet (Table 1) supplemented with milking concentrate. The experimental groups were fed a milking concentrate containing 20% of bean seeds. Group MI was fed the Mistral cultivar with a low anti-nutritional content; the Merkur cultivar with high anti-nutritional content was fed to group ME; and group MET was fed the Merkur cultivar whose content of anti-nutritional substances was reduced technologically. This technology based on patent No. 285745 was further modified by adjusting the reactor temperature, the duration of exposure to that temperature and the duration of ageing of the material thus treated. The control group was fed the milking concentrate with a higher proportion of extracted soybean meal and grain meal. The dairy cows were fed the experimental diet for 12 weeks. The composition of milking concentrate for the control and experimental groups is detailed in Table 2. All milking concentrates had an analogical content of nutrients (Table 3). The levels of anti-nutritional substances in individual bean cultivars are detailed in Table 4. Feeding procedures were similar for all groups. Milking concentrates were supplied to troughs according to the level of expected milk yield, starting with milk yield guaranteed by basic diet (10 l) in a ration of 400 g per one l of milk. Single ration never exceeded 2 kg. The expected milk yield of 30 l was then ensured by 8 kg of milking concentrate. Changes to the milking concentrate were done gradually in the course of 5 days. The metabolism of dairy cows was examined via regular blood, urine and rumen fluid sampling. The first samples 58 Table 1. Composition of basic diet for control and experimental groups at an expected average milk yield of 30 l