Effects of new feeding system on feed intake, milk production, manure production and methane production of dairy cows

3.1.1 Chemical composition of feedstuffs

The chemical composition of feedstuffs used in the diets of dairy cows is showed in Table II.

TABLE II. CHEMICAL COMPOSITION OF FEEDSTUFFS

*UTRS – urea treated rice straw

Data on Table II showed that most of the feedstuffs in dairy cattle diets have a high content of water So that dry matter of feedstuffs is low: Grass 15.6%, cassava waste 17.2%, brewery waste 22.6%. On the other hand, untreated rice straw and cassava waste have a low content of protein: 4.6% and 2.6%. Grass and untreated rice straw have a high content of fibre: 30.2% and 32.6%.

There were many studies on treatment of feedstuffs, especially fibre by-products in other to increase nutritive values. Doan Duc Vu et al., 1999^a; Doan Duc Vu et al., 1999^b; Doan Duc Vu, 2000; Nguyen Xuan Trach, 1998; Nguyen Van Thu, 1997; Vu Van Noi et al., 2001 have studied on treatment of rice straw with urea. Bui Van Chinh, 2001;

Nguyen Thi Tu, 2001 have results of treatment of sugarcane leaves and bagasses. Bui Xuan An, 1998; Doan Duc Vu, 2004 have studied on peanut vines and pineapple waste silages. It concluded that the fibre by-products can be improved with some treatment methods.

3.1.2 Effects of new feeding system on feed intake of dairy cows

The quantity of feedstuffs and nutritive values of diets are showed in Table III.

ccording to NRC, nutrient requirement of a dairy cow with 450 kg of body weight and 16 kg of milk yield is 13.10 kg DM, 2.80 kg CF, 1.80 kg CP and 33.55 Mcal ME. Data of Table III showed that a dairy cow could intake 23.4 kg grasses, 1.8 kg of untreated rice straw, 4.8 kg of cassava waste, 6.8 kg of brewery waste and 6.2 kg of concentrate. Daily DM intake and energy was not enough compared to requirement while fibre content was high but protein content was low. When rice straw has been treated with urea and UMMB was supplemented, the nutrient value of the diet has been improved. All of nutrient indices including DM, CF, CP and ME have been met compared requirement.

TABLE III. FEED INTAKE OF DAIRY COWS FED DIFFERENT DIETS

Indices Group 1 Group 2

Feed intake (kg/day) - Grasses

- Untreated Rice straw - Urea Treated Rice Straw - Cassava waste Nutrient value of diet (kg/day)

- DM

a,b Mean within rows with different superscripts differ significantly (P<0.05)

There are some methods for improving dairy cattle diets in Vietnam condition.

Under project RAS/5/030, RAS/5/035 and other national and international projects, UMMB technology was widely disseminated and adopted by farmers in many regions in the whole country (Doan Duc Vu et al., 1999; Nguyen Van Thu et al., 1993; Bui Xuan An et al., 1993; Bui Van Chinh et al., 1993). With crude protein around 25%, cassava hay fed with 2kg/herd/day helps to balance the energy and protein ratio in dairy cattle diets. This protein stimulates both productivity and efficiency of roughage utilization (Doan Duc Vu, 2003). Supplementation of whole cottonseed or cottonseed meal with amount of 2 kg resulted to have a long peak of lactation of dairy cows (Dinh Van Cai, 1999).

3.1.3 Effects of new feeding system milk production, manure production and methane production of dairy cows

The milk production, milk composition, manure production and methane production are showed in Table IV. Data of Table IV showed that, with the new feeding system (urea treated rice straw + UMMB) milk production of dairy cows increased considerable (P<0.05) compared to control group: 16.27 vs. 15.01 kg/cow/day. Milk composition (DM, fat and protein) also has been improved but differences of data between two groups were not significant. The costs of feedstuffs for one kg of produced milk in new group was lower 0.06 USD/kg than that in traditional feeding group (0.19 vs.

0.25 USD/kg). The amount of produced manure of dairy cows in group two was higher than that in group 1 (P<0.05): 24.5 vs. 21.6 kg/cow/day while methane production of dairy cows decreased when the animal diet has been intervened.

TABLE IV. MILK PRODUCTION, MANURE PRODUCTION AND METHANE PRODUCTION OF DAIRY COWS FED DIFFERENT DIETS

No. Indices Unit Group 1 Group 2

a,b Mean within rows with different superscripts differ significantly (P<0.05)

Milk production has been improved due to using urea treated rice straw, UMMB leading a suitable rumen environment for activities of microorganisms. Many authors have proved these results such as Doan Duc Vu 2000, Bui Van Chinh and le Trong Lap, 1996. Methane is produced during the digestion in the rumen of ruminants. Low quality roughage, the nutritionally imbalanced diets, especially energy and protein are main factors effecting methane production. Thus, treating of roughages, feed supplementation, balancing the ration and improving the environmental condition of cattle sheds are basic methods to decrease methane production, to improve efficiency of feed utilization and to increase productivity of ruminants.

In the previous time, the measurement of methane production from livestock has not been considered. However, yet in two recent years, within the framework of cooperation with International Livestock Research Institute (ILRI), we tried to use simulation model software, which can determine the methane production on each

individual animal, on each kg of milk or meat produced. This software can help estimating the changing of methane production between different souses of feedstuff and those from different rearing methods.

The appropriate strategies for reduction of methane production are still mainly base on feeding strategies, in which treatment of roughage, use of feed supplementation, balancing the ration could be applied to the farm household. Saadullah, 1981 concluded that while 0.126 kg methane produced per kg live weight gain with urea treated straw, it was 0.84 kg per kg live weight gain with untreated straw. Saadullah, 1992 proved that the methane production per unit of product can be reduced by 25% to 75% allowing urea molasses block, fish meal, oil cakes etc. Ionophore feed additives (monensin sodium) supplementation into concentrate feeds to promote propionate and reduce methane production by 16-24% in steers (Thromton and Owens, 1981).

3.2 Effects of new manure management on manure quality, grass yield and soil