Two experiments were conducted to investigate the effects of local plant feed resources, sunflower oil and coconut oil on rumen fermentation, digestibility, voluntary feed intake, milk yield and composition in lactating dairy cattle.
In the first experiment, eleven local feed resources were studied, as follows: mangosteen (Garcinia mangostana) peel (MSP), guava (Psidium guajava) leaf (GVL), siam neem tree (Azadirachta indica) leaf (SNTL), sesbania (Sesbania grandoflora) leaf (SBNL), coral leaf (Eritrina variegate) (CRL), Bai Yanang (Tiliacora triandra) (BY), cassava hay (Manihot esculenta, Crantz) (CH), bitter cucumber (Mormormdica charantia) fruit (BCF), banana (Musa sapientum) leaf (BNL), mulberry (Morus indica) leaf (MBL), and Plia farn (Macropanax dispermus Ktze) leaf (PFL). Approximately 5 g of feed samples were weighed into duplicated nylon bags (38 µm pore size) and incubated ruminally at 0, 2, 4, 8, 12, 24, 48, and 72 h-post feeding. The results showed that the mean values of ruminal pH (6.6) and temperature (38.8 ºC) were not different (P>0.05) among different times of incubation. The condensed tannins (CT), and crude saponin (CS) values of local plants were 15.8 and 9.8 % for MSP, 14.8 and 2.8 % for GVL, 11.0 and 2.5 % for SNTL, 4.0 and 2.0 % for SBNL, 2.3 and 1.8 % for CRL, 2.2 and 1.7 % for CH, 2.2 and 1.3 % for BY, 2.1 and 4.1 % for BCF, 2.0 and 1.4 % for PFL, 1.7 and 1.3 % for BNL, and 1.6 and 2.3 % for MBL, respectively. The highest and lowest values of the potential degradability (a+b) and effective degradability of DM and OM of the feed resources for PFL and MSP were 97;72.3, 98.1;73.2 and 58.6;46.7, 59.1;45.7 %, respectively. It was also shown that PFL had a higher (p<0.01) rumen degradability, while MSP had the lowest, thus resulting in higher rumen degradable and undegradable roughage sources, respectively. Based on these results PFL could be used efficiently in the rumen and MSP as a rumen by-pass protein due to its CT and CS contents.
The second experiment was conducted on famer’s farm in Muang district, Khon Kaen province. Five crossbred dairy cows (75% Holstein-Friesian), at 100-150 days-in-milk (DIM) and with 450±50 kg BW were used to evaluate the effects of mangosteen (Garcinia mangostana) peel, sunflower oil and coconut oil supplementation on feed intake, nutrient digestibility, ruminal fermentation, milk yield and milk composition. Experimental design was a 5 x 5 Latin square design. Cows were fed rice straw and ruzi grass (Brachiaria ruziziensis) ad libitum. Concentrate feed was fed based on milk production of 1 kg concentrate to 1.5 kg milk production. Five supplemented treatments were control (no supplement) and two levels of mangosteen peel at 100 and 200 g DM/hd/d with (MSP100-SFCO, MSP200-SFCO) or without (MSP100, MSP200) adding 6% vegetable oils (3% sunflower oil and 3% coconut oil) to the concentrate supplement. Each feeding period lasted for 21 days during which feed intakes and milk yield were recorded. The results revealed that level of mangosteen peel supplementation or supplementation with vegetable oil did not affect nutrient digestibility, blood-urea-nitrogen, or milk production and composition. However, dry matter intake was significantly reduced with supplementation of mangosteen peel with vegetable oil (3.1, 3.1, 3.0, 2.8 and 2.7 % BW) for control, MSP100, MSP200, MSP100-SFCO, and MSP200-SFCO, respectively. Ruminal ammonia-nitrogen and acetic acid (C2) concentration were significantly lower, while propionic acid concentration (C3) was higher in supplemented groups, especially in the mangosteen peel supplementation with vegetable oils when compared with the control group. Supplementation of mangosteen peel only or with vegetable oils in the diet reduced rumen protozoal population significantly (P<0.05) (13.7, 11.9, 12.8, 8.8 and 9.7x105 cell/ml for control, MSP100, MSP200, MSP100-SFCO, and MSP200-SFCO, respectively), while the rumen bacterial population was significantly increased as compared to the control group. The MSP100-SFOCO group had a higher milk yield (FCM) and higher fat content and hence, resulted in higher income return. Based on this study, a conclusion can be made that supplementation of mangosteen peel at 100 gDM/d with vegetable oils could be beneficial for dairy cattle fed a rice straw, and ruzi grass (Brachiaria ruziziensis) based diet. The benefits were due to improved rumen ecology, especially the bacterial population, and reduced concentrate cost, hence with higher economical returns.
In summary, results from the two experiments revealed that local feed resources containing variable levels of CT and/or CS could be used as alternative strategic supplements to improve rumen ecology. Feeding fat by a combination of SFO and CO in dairy cattle could be a way to meet energy requirement to increase milk yield and composition. These findings would be very useful for small-holder farmers to improve feed utilization efficiency and production. However, studies on level of CT and SP in feed resources and level of energy and protein require future research.