In order to compare effects of feeding systems on rumen fermentation characteristics and nutrient digestion, steers were fed either total mixed ration (TMR) or separate concentrate-roughage ration (CR). Total tract digestibility of nutrients was higher in steers receiving TMR. Especially, DM, ADF and NDF in TMR were digested to a greater extent than those in CR. Rumen pH was not influenced by the feeding systems. Holstein steers on TMR had higher ruminal NH3-N than those on CR. Feeding system did not alter VFA production but TMR feeding resulted in lower A/P ratio. TMR feeding tended to increase the number of bacteria and protozoa in the rumen fluid. Also steers fed TMR generally had higher fiber degrading enzyme activities, which might be the result of increased number of cellulolytic microbes in the rumen of animals on TMR. Our results indicate that TMR may provide more favorable condition for nutrient digestion both in the rumen and in the total tract of steers. (Asian-Aust. J. Anim. Sci. 2003. Vol 16, No. 10 : 1482-1486)

Effects of Feeding System on Rumen Fermentation Parameters and Nutrient Digestibility in Holstein Steers

Feeding measures with a potential to improve N efficiency in dairy cattle husbandry were studied at two levels of undegradable protein balance (OEB). In each of the two experiments, two simultaneous Latin squares were conducted, each with three treatments and three lactating Holstein cows. Decreasing the OEB of the diet improved N efficiency and resulted in lower N excretion per kg milk. To avoid a negative effect of the decreased OEB on the production results, spreading the concentrate intake (as TMR or in five meals) seemed to be most promising, although only few significant effects were found. The use of protected protein sources or the addition of clinoptilolite were not successful in improving N-efficiency. The rather well balanced mixed basal diet and the large variation between animals seem to have hampered the assessment of such significant influences.

Feeding measures to reduce nitrogen excretion in dairy cattle.

This study was designed to evaluate the effects of two feeding methods on milk yield, composition and fatty acid (FA) profile obtained from dual-purpose cattle. Twenty-four Aosta Red Pied cows beyond peak of lactation were assigned to two groups and fed hay and concentrates in the proportions 0.69 and 0.31 on a dry matter basis for 10 weeks. Concentrates were offered separately from forages 6 times a day (separate ration, SR) or as a total mixed ration (TMR). The feeding method did not significantly influence dry matter intake (16.8 vs. 16.9 kg/head/day for SR- and TMR-fed cows, respectively), milk yield (17.4 vs. 17.5 kg/head/day), milk fat, protein and lactose contents (36.4 vs. 35.2, 33.5 vs. 32.8, and 47.3 vs. 47.4 g/kg) and yields (607.9 vs. 613.4, 567.4 vs. 572.7 and 805.5 vs. 829.7 g/head/day). The overall milk FA profile was very similar between groups. Milk concentrations of FA used as indirect markers of rumen function (C18:2 t10c12, odd- and branched-chain FA) and the extent of ruminal biohydrogenation were comparable (P > 0.05) between SR- and TMR-fed cows, suggesting that ruminal pH did not vary considerably as a consequence of the feeding strategy applied.

Milk yield, gross composition and fatty acid profile of dual‐purpose Aosta Red Pied cows fed separate concentrate‐forage versus total mixed ration

The purpose of this experiment was to investigate the effect of the diets supplemented with lard or prilled fat (Carolac  ) on lactation performance, plasma constituents and ruminal characteristics of Holstein cows under a warm climate. In trial 1, 18 Holstein cows, 14 primiparas at 43 DIM and 4 multiparas at 55 DIM, were randomly assigned into six 3×3 Latin squares, in which three dietary treatments were isoproteinous but varying in energy contents and three 21 d periods. The treatments were basal diet (Control), basal diet supplemented with 2.5% lard (LD), and basal diet supplemented with 2.5% commercial Prilled fat (PF). In trial 2, three rumen canulated pregnant nonlactating Holstein cows with 550 kg average body weight were allotted into a 3×3 Latin square design with diets same as in trial 1 were fed to the cows at the level of 1.5% body weight on dry matter (DM) basis. The results indicated that the DM intake did not differ among the treatments. Milk yield and 4% FCM yield were greater (p<0.05) in PF than in Control. LD and PF resulted in greater milk fat percentage. Protein, lactose and solid contents in milk were not different among the three dietary treatments. The concentration of nonesterified fatty acids (NEFA) in plasma was significantly greater in LD and PF than that in Control. However, the concentrations of triglycerides, urea nitrogen, and cholesterol in plasma were not significantly different among the three treatments. Although the ruminal molar percentage of isobutyrate in LD and PF was greater, no significant difference was observed in ruminal pH, NH3-N concentration and VFA production among the three treatments. Diet supplemented with fat can improve milk yield and milk fat percentage without resulting in disadvantages of ruminal characteristics in cows at early lactation and under warm climate. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 2 : 213-220)

Dietary Supplementation of Fat Increased Milk Fat Percentage without Affecting Ruminal Characteristics in Holstein Cows in a Warm Tropical Environment

The Effects of Total Mixed Ration and Separate Feeding on Lactational Performance of Dairy Cows

This study was conducted to determine a proper feeding regime for lactating Holstein cows during the warm season in Taiwan. In Feeding Trial, 21 lactating Holstein cows were randomly allotted into three feeding regimes in a Completely Randomized Design. The feeding regimes were roughage fed ad libitum along with concentrate fed either twice daily (2C) or four times daily (4C), and total mixed ration (TMR) for 8 weeks. No significant differences among the three feeding regimes were found in body weight changes, and intakes in terms of dry matter, crude protein and net energy. For milk yield and 4% FCM yield, 4C were higher than the other two feeding regimes (p<0.05). No significant differences were found in milk compositions or differences noted in the yields of the respective milk components. TMR was worse than 2C and 4C (p<0.05) in milk production efficiencies in terms of dry matter intake per kg milk yield, crude protein intake per kg milk protein yield, as well as dry matter intake, net energy intake and crude protein intake per kg 4% FCM yield. Three ruminally fistulated Holstein dry cows were randomly assigned into the same three feeding regimes in a 3×3 Latin Square Design. No significant differences were found among the feeding regimes in ruminal pH, ammonia nitrogen, total VFA concentration, molar percentages of VFA, and acetic acid: propionic acid ratio (C2/C3). Taken all together, roughage fed ad libitum and concentrate fed four times daily was the better feeding regime for lactating cows during the warm season in Taiwan. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 5 : 658-664)

Yaun-Lung Lin

Papers

Effect of Concentrate Feeding Frequency versus Total Mixed Ration on Lactational Performance and Ruminal Characteristics of Holstein Cows