Development and Evaluation of Broccoli By-product Silage as a Substitutional Ingredient of TMR for Dairy Cows

Abstract

One way to achieve a sustainable livestock industry is to increase the by-product utilization from agriculture and feed industry. However, commercial use of agricultural by-product has been limited due to the lack of information on the value of feed, methods of use, and harmful components of natural food resources. In Pyeong-chang, Gang-won province, Korea, over 4,000 t of broccoli flowers are grown annually, but their by-products (stems and leaves) of about 6,000 t per year are discarded. Therefore, a study was designed to establish the optimal broccoli by-products silage formula using a combination of various additives and to test the cow's performance in a dairy cattle feeding trial to determine whether it would be valuable a substitute to the commercial dairy TMR.

Chopped broccoli by-products (BB) have been mixed with several agricultural by-product additives with or without lactic acids bacteria (LAB) inoculation in a series of silage preparation trial. And feed value, feed fermentation quality and palatability was tested to establish optimal formulation for broccoli by-product silage (BBS). The optimal BBS was obtained when BB combined with beet pulp & wheat bran (20% of the total silage weight) and L. plantarum inoculum (5 × 107 cfu/kg). The mixture was put into 20L plastic box as tight as possible to remove air and covered with lid, and incubated in a barn for 45 days. BBS resulted in high levels of CP (19 %), TDN (71.7 %), NEL (1.67 Mcal/kg) and high quality fermentation with high lactic acid content. For the feeding trial, 9 ton of BBS was prepared using a TMR mixer to chop the BB and mix well the additives. Silage was put into vinyl-lined ton-bag with tight pressure to remove air. BBS was incubated in a barn condition for 45 days. 27 Holstein cows were need to test the feed value of BBS. Control cow feed was 20 kg of commercial TMR (Cargill agri-purina, Korea) mixed with chopped 10 kg of rye silage, total 30 kg of TMR feed was fed daily. Test TMR was prepared mixing 10 kg of chopped rye silage and 16 kg of commercial TMR and 10 kg of BBS which replaces 20 % (4 kg) of commercial TMR. The feeding trial lasted for 8 weeks

the first 4 weeks were control period feeding control TMR feed and the next 4 weeks was test period feeding test TMR. 27 Holstein cattle data was separated to 4 groups according to days in milk (DIM) (group A: 238 ± 90.1, B: 146.8 ± 22.9, C: 73.9 ± 6.9, D: 23.5 ± 12.6). The milk yield was verified by comparing the slope of the test period with the control period using the daily milk yield data from individual cow collected. Milk sampling was conducted once a week to analyze the components and functional substances. As a result, it was determined that there was no significant difference in the milk yield compared to the control period. It was also determined that there was no significant difference in the milk components including milk fat, protein, lactose, SnF, MUN compared to the control period. We judged that BBS did not affect the change in the milk production. Also, analysis of functional substances in silage showed that sulforaphane a key functional molecule for anti-cancer decreased by about 99 % and beta-carotene increased by 120 % during the BBS fermentation (p < 0.001). In addition, antioxidant activity increased by about 55 % (p < 0.005). During the test period, the beta-carotene content in milk significantly increased in most groups (linear, p < 0.05), but vitamin A showed no significant change. Total phenolics content (TPC) tended to decrease in most groups, while antioxidant activity tended to increase. Therefore, BBS had a high deed feed value and fermentation quality and concluded that when replacing 20 % of commercial dairy TMR with BBS, it did not adversely affect to the cows milking performance. We also believe that the use discarded BB as feed are important to improve the sustainability of livestock industry in Korea and there are good potential for BBS as a TMR ingredient at least in dairy cows.