Feed intake relative to stage of lactation for dairy cows consuming total mixed diets with a high or low ratio of concentrate to forage

Two grass silages made from perennial ryegrass, and with D-values of 0·216 and 0·255, were offered ad libitum to 18 Ayrshire cows in two feeding experiments. On the control treatment the silages were supplemented with soybean meal only, and on the other two treatments with equal weights of DM from either barley or dried molassed sugar-beet pulp plus the same weight of soya as on the control treatment. The daily intakes of silage DM were not significantly different on the barley and beet-pulp treatments, and, on average, the intake of silage DM was reduced by 0·24 and 0·20 kg by feeding 1 kg barley and beet pulp DM respectively.



The daily milk yields were not significantly different on the barley and beet-pulp treatments with mean values of 19·2 and 19·2 kg per cow respectively compared with 17·2 kg on the control treatment. On the barley and beet-pulp treatments the fat, SNF, CP and lactose concentrations in the milk and the live weights of the cows were not significantly different. It is concluded that the barley and beet pulp had similar feeding values and replacement rates when used as supplements with grass silage, and that the two feeds were interchangeable on an equal DM basis.

Silage and milk production: a comparison between barley and dried sugar-beet pulp as silage supplements.

Effective utilization of available feed resources is the key for economical livestock rearing. Complete feed system is one of the latest developments to exploit the potential of animal feed resources in the best possible way. The complete feed is a quantitative mixture of all dietary ingredients, blended thoroughly to prevent separation and selection, fed as a sole source of nutrients except water and is formulated in a desired proportion to meet the specific nutrient requirements. The concentrate and roughage levels may vary according to the nutrient requirement of ruminants for different production purposes. The complete feed with the use of fibrous crop residue is a noble way to increase the voluntary feed intake and thus animal’s production performance. In this system of feeding, the ruminant animals have continuous free choice availability of uniform feed mixture, resulting in more uniform load on the rumen and less fluctuation in release of ammonia which supports more efficient utilization of ruminal non-protein nitrogen. Feeding complete diet stabilizes ruminal fermentation, thereby improves nutrient utilization. This feeding system allows expanded use of agro-industrial by­products, crop residues and nonconventional feeds in ruminant ration for maximizing production and minimizing feeding cost, thus being increasingly appreciated. However, to extend the concept extensively to the field and make this technology successful and viable for farmers, more efforts are needed to be taken.

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Prospects of complete feed system in ruminant feeding: A review.

The voluntary food intake of pregnant and lactating ruminants: a review.

Manners, M. J. & McCrea, M. R. (1963). Br.J. Nutr. 17, 495. Mayer, J. (1953). New Engl. J. Med. 249, 13. Snyderman, S. E. & Holt, L. E. Jr. (1961). 4: Pediat. 58, 237. Widdowson, E. M. (1947). Spec. Rep. Ser. med. Res. Coun. no. 257. London: H.M. Stationery Office. Widdowson, E. M. (1950). Nature, Lond. 166, 626. Widdowson, E. M. & McCance, R. A. (1960). Proc. R. SOC. 8. 152, 188. Widdowson, E. M. & Spray, C. M. (1951). Archs Dis. Childh. 26, 205. [C. .F Code, editor]. Washington, D.C. : American Physiological Society.

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Physiological changes affecting voluntary food intake in ruminants.

Twelve Friesian heifers were given four dietary treatments from 2 months before first calving to the end of the first lactation. Two of the treatments involved the ad libitum feeding of a complete diet consisting of a basal concentrate meal of rolled barley with supplements, incorporated into a mixture with either hay or barley straw both coarsely ground and included at a level of 25 % of the complete mix. In the other two treatments either the hay or the straw was given ad libitum in the long form and the concentrate mix fed ad libitum from a separate self-feeder.Full records were kept of the intake of food and water, the output and quality of the milk and of live weight. Detailed measurements were made of various aspects of rumen function using one cow on each treatment fitted with a cannula. Rumen samples were also obtained from non-fistulated cows by stomach tube.The intake of long roughage, particularly straw, by the cow, when offered in conjunction with a separate supply of the concentrate mix, was very low and led to serious falls in milk butterfat content. Where the roughage was incorporated into the complete diet normal butterfat levels were maintained. However, apart from the depressed butterfat levels on the two long roughage treatments the health and condition of the cows remained good.The very low intake of long straw was associated with a smaller volume of liquid in the rumen, a reduced rate of flow of liquid leaving the rumen, a lower proportion of acetic and butyric acids and a greater proportion of propionic acid in the rumen liquor and finally with a higher blood glucose content. The inclusion of milled roughage resulted in values within the normal range for volume of liquid in the rumen, flow rate of liquid from the rumen, V.F.A. proportions in the rumen liquor and blood glucose.The intake of both food and water over the productive cycle showed a consistent pattern for all cows. Food intake reached its lowest point around calving followed by a sharp rise to a peak in the 4th month after calving and then a gradual but increasing decline. Water intake followed a similar pattern but the fluctuation was greater and the peak consumption occurred in the 3rd month of lactation. Water intake was more closely associated with D.M. intake than with milk output.The efficiency of utilization of the complete diets containing the milled roughages is discussed in relation to comparable data from cattle fed conventionally.

A study of the voluntary intake of food and water and the lactation performance of cows given diets of varying roughage content ad libitum.

Complete diets were given ad libitum to dairy cows over a whole lactation in order to study the voluntary intake of food, lactation performance and efficiency of feed conversion The effect of including four levels 16, 24, 32 and 40 % of coarsely milled barley straw in the loose mix was studied for diets based mainly on barley or on sugar beet pulp, using a double 4 × 4 Latin square designThe results confirmed that cows can perform normally when given complete diets for extended periods Dry matter and digestible energy intake was depressed at the higher levels of straw inclusion and milk butterfat content at the lowest level The net efficiency of conversion of metabolizable energy (ME) into milk was higher at the higher levels of straw It is concluded that complete diets for the self-feeding of dairy cows should contain a minimum of about 24 % of coarsely milled straw and that estimated metabolizable energy intake and production were depressed by including straw at higher levels

Complete diets given ad libitum to dairy cows—the effect of the level of inclusion of milled straw

Summary Twelve Friesian cows were given six complete diets ad libitum in an experiment designed as a double 6 × 6 Latin Square balanoed for residual effects. The main energy components of the diets were rolled barley and 20, 35 or 50% chopped barley straw. The diets were given either as a loose mix or extruded through a fin. die. Dry-matter intake, milk yield and solids not fat % declined while butter fat % increased progressively with increased levels of straw in the complete diets which were fed in the loose form. In comparison with the loose diet containing 20% straw, the corresponding cubed diet was associated with a depression in dry matter intake and a decreased butterfat %. In contrast, the oubed diets containing 35 and 50% straw supported higher dry-matter intakes, higher solids oorrected milk yield but lower butter fat % than the corresponding loose diets. The effect of cubing the 35 and 50% straw diets was to make the voluntary dry-matter intakes and lactational performances comparable to those obtained with the loose mixes containing 20 and 35% straw respectively. In general the voluntary intake data agrees with a previously proposed model. However, the depressed intake obtained with the 20% straw diet in the cubed form would not have been predicted by the model. It is suggested that complete diets could be used in large units to combine the low labour costs of self feeding of dry feed with a high degree of control over nutrient intake and laotational performance.

P. S. Bridge

Papers

A study of the voluntary intake of food and water and the lactation performance of cows given diets of varying roughage content ad libitum.

Complete diets given ad libitum to dairy cows—the effect of the level of inclusion of milled straw

Complete diets given ad libitum to dairy cows: the effect of straw content and of cubing the diet.