Ruminal Biohydrogenation Modification and Unsaturated Fatty Acid Supplementation to Enhance Conjugated Linoleic Acid in Milk

Abstract

Recently, people have become increasingly aware of their health by consuming bioactive compounds such as Conjugated Linoleic Acid (CLA) found in CLA-rich milk. Various factors, such as the type of feed, environmental conditions, fatty acid content, and biohydrogenation processes in the rumen, influence the synthesis of CLA in milk. To date, there has been limited research on optimizing feed selection, environmental conditions, fatty acid (FA) content in the feed, and protection against biohydrogenation in the rumen to produce CLA-rich milk. In general, this research aims to produce CLA-rich milk through a series of studies with specific objectives: (1) Selecting the type of forage, its environmental origin, and in vitro fermentation biohydrogenation processes that have the potential to provide precursors and the best conditions for CLA synthesis, (2) Choosing the supplementation of high unsaturated fatty acid (UFA) oils and their inclusion levels in the diet that do not disrupt rumen fermentation and digestion, and (3) Testing the diet with the best forage type and protected oil supplements to achieve the highest milk production and CLA content. This research's first phase was to select the type of grass, its origin, and harvest age that contains the best FAs for healthy milk fat synthesis. Forage was the primary and most cost-effective source of FAs, including CLA, which influences milk FAs. The first phase of the research aims to analyze fermentation, digestibility, biohydrogenation, nutritional composition, and FAs of diets consisting of elephant grass (EG) and king grass (KG). The forage was obtained from highland (Pangalengan Regency) and lowland (Dramaga Regency) areas, with three different harvest ages (1, 1.5, and 2 months). The diets were then analyzed for their nutrition and FAs. In vitro research was conducted to analyze in vitro fermentation, biohydrogenation, and digestibility. The treatments showed significant differences in NH3 levels, ranging from 5.31 to 8.86 mM. The highest NH3 levels were found in diets containing highland EG harvested at 1.5 months. Dry matter digestibility (DMD) values ranged from 58.27 – 64.39 %, and organic matter digestibility (OMD) values ranged from 61.07 – 67.18 %. Different digestibility values were found for different harvest ages, with an interaction between elevation and harvest age. This aligns with the content of cellulose, neutral detergent fiber (NDF), and lignin in the grass. The highest digestibility was found in EG at 1.5 months. Diets containing KG significantly produced higher C18:0 and trans C18:1 than diets containing EG. The lower content of C18:0 and trans C18:1 in EG diets was likely due to partial biohydrogenation processes. Inhibition of the biohydrogenation process was suspected to be caused by the phenolic content in EG grass. Thus, it can be concluded that highland EG at 1.5 months was a potential diet to support healthier FA production in milk. The study's second stage was to choose the high UFA oil supplementation used. High UFA supplementation oil is believed to improve milk FA, including CLA. The study aimed to analyze the effect of oil high in UFA supplementation on the fermentation and digestibility of the ration. The ration contains 40 % EG and 60 % commercial concentrate. The ration was then supplemented by peanut, soybean, olive, and lemuru fish oil with three different levels (0, 2, 4 %). The oils were analyzed for their FA profile. In vitro study was done to analyze the fermentation and digestibility. There were significant differences in pH in the range 6.81–7.13. The highest pH was found in a ration supplemented with olive and peanut oil. The DMD were 65.38–69.61 %, and OMD were 67.29–71.72 %. Significant differences in DMD were found in different levels, significantly decreasing in 4 % supplementation. OMD was found to be significantly different in level and oil types. The highest OMD was found at a ration supplemented by lemuru oil. The proportion of nC5 decreases significantly as oil supplementation increases. No significant differences were found in C2, C4, and C2/C3 ratios that were important in estimating milk fat synthesis. In conclusion, the ration with lemuru oil supplementation is a potential ration to further modification to support healthier FA production in milk. The last stage was an in vivo trial. Lemuru oil supplementation in dairy cow rations in vivo has shown no adverse effect on rumen fermentative, and it has the potency to act as a high-energy feed to meet the needs of environmental challenges in livestock in tropical regions such as Indonesia. This last stage study aimed to examine the effect of protected fat supplementation from calcium (Ca) soap lemuru fish oil and prill fat on the production and quality of milk FAs in lactating dairy cows in lowland areas, Bogor Regency, Indonesia. The 16 lactating dairy cows were randomly assigned into four treatments and four groups (4 × 4). The four treatments consist of control (C), 1 % Ca soap lemuru oil (1%LS), 2 % Ca soap lemuru oil (2%LS), and 2 % prill fat (2%PF). The four treatments acted as fixed factors, each cow acted as a random factor, data were analyzed using Mixed-Design ANOVA, and significant differences were further analyzed using DUNCAN. Significant differences were found in morning milk production, fat content, nutrient consumption, methane gas production, and ration cost (Rp/cow/day). Morning milk production increased in rations with fat supplementation, with the highest increase in supplementation at 2 %. An increase in milk fat content was found in the 1%LS treatment, and milk fat depression was found in the 2%LS and 2%PF treatments. Nutrient consumption remained unchanged in the 1%LS treatment but decreased in the 2%LS and 2%PF treatments, except for EE consumption, which increased in the Ca soap treatment. There was a tendency for increased methane production in the Ca soap treatment. The increase in feed price (Rp/cow/day) did not affect the feed price per liter of milk, with a tendency for increased efficiency in rations with fat supplementation. In conclusion, the 1%LS treatment exhibited higher milk fat content and production than the other treatments.