Feeding High-Producing Dairy Cows

Ofer Kroll -HaChaklait

Until the end of the 50's, most of the dairy herds in Israel were relatively small. Dairy barns were of the stanchion-stall type for the most part, with 110-cm manger space per cow. Each cow had its individual place where she ate, rested and was milked. This type of building lent itself to individual feeding, each cow receiving a portion of concentrate and/ or forage several times a day, mainly according to yield. As number of cow?s increased and central milking parlors gained popularity, herds were divided into groups. Grouping was done according to stage of lactation and yield. With this system and especially as a result of crowding cows into the various groups, it became clear that every cow that calved and entered the highest group pushed out another into a lower group almost automatically. This system proved damaging to the milk yield of the transferred cow and was of special disadvantage to the younger and relatively smaller cows who were unable to match the older cows in the competition for feed.

It is well known that young cows have a relatively greater persistency of milk yield during their lactation, and if deprived of sufficient feed their development and growth will suffer. Many farms today separate heifers from more mature animals. For these young cows one uniform level of feeding is being practiced and little attention is paid to feeding norms, on the assumption that whatever feed was offered above requirements for milk yield would be utilized for growth, this producing a better mature animal. The general approach in Israel today is of maintaining 3 feeding groups: one consisting of heifers, one for early lactation and one for high potential cows. In family farms, the one-diet method is the most popular. Liberal feeding, mainly with TMR mixer and minimum transfer of cows between groups is the preferred feeding method in Israel.

Ration Programming and Feeding Practices
Optimal planning and rationing have always been desirable goals from a professional and economic point of view; however, one should take care in adjusting planning to management.

Feed Intake
The system of group feeding, carried-out with the use of the weighing mixer wagon, represents an important management tool for dairy and beef farms. As well as improving feed efficiency and rumen fermentation, it provides control of feed intake.
It has been shown that an average daily feed intake, expressed in dry matter, ranges from 3.0 to 3.5% of body weight and depends on milk yield, days after calving, ration composition, NDF content, forage: concentrate ratio, particle size and density of ration. In Israel, the influence of the summer climate also has a profound effect, contributing to a 10-15% decline of feed intake in summer, as compared to winter. Feed intake, especially with cows at peak lactation, constitutes the major limiting factor to feeding and the provision of nutrients. This is the starting point in any system of rationing and planning. Perhaps once we have at our disposal protected proteins and fats we shall be able to overcome the limitation of conventional energy intake.
From feeding TMR ad-lib, we have data of feed intake for the group but not enough data on the intake of individual cows. It appears that the maximum individual intake by high yielding cows reaches up to 4% of their body weight (or NDF up to 1.3% of body weight).

Energy Level
Until the end of the seventies, the Scandinavian feed unit was commonly employed for rationing in Israel. It used the average norm of 5 feed units a day for maintenance and 0.3-0.4 feed units per 1 kg of milk. As the available amount of roughage is limited, this led to feeding cows 17-18 kg of concentrate per day, resulting in lower feed efficiency. With the increased use of the metabolic and net energy (ME, NEL) systems and their higher evaluation of roughage, the importance of roughage has become more emphasized. Evidently, the manipulation of the feeding level cannot be achieved by changing the amount of concentrates alone.
Today it is common to use the ME/ NE system for energy evaluation and NDF or ADF for intake and energy estimation.
NRC 89-01 in addition to local experience, is the main guideline for feeding high-producing dairy cows, but under low quantity/ low quality roughage conditions, high energy concentration is common practice. The energy concentration for high yielding cows under Israeli conditions is about 1.75-1.76 Mcal NEL kg DM diet. Fat content is between 3% to 5%, and various sources of starches are always included.

500-550 grams of crude protein for maintenance and about 70 gram per kg milk were a typical allowance. To day, In the TMR system 16%- 16.7% crude protein is the requirement for high yielding cows (in summer and winter, respectively). About 34%-36% of the total protein is from UIP (Undegradable Intake Protein) and a large variety of protein sources are a common solution to cover the needs for the different amino acids.

Under Israel's conditions of feeding, it is important to estimate the animal's requirement of NDF, which will allow normal rumen function. The use of intermediate feeds, such as wheat bran or orange peel, takes the amount of NDF to a total of 6-6.6 kg per cow per day (30%-34% of total dry matter), but with forage NDF not more than about 3.4-3.6 kg (17%-18% of total dry matter). Particular attention must be paid to the physical structure of feeds; straw, when finely chopped looses some of its efficiency as roughage.

Additional Measures
For the calculation of the correct composition of rations, especially when using computers, there are a number of basic assumptions regarding local conditions, which may not have any justification in literature or in research but which appear, from farm experience, to have an influence on feed intake and performance. .
Intermediate feeds: feeds containing large amounts of highly digestible carbohydrates, such as beet pulp and orange peel are limited to 15% in order to prevent acidosis. In this group of foodstuffs one can include liquid whey, nowadays used extensively in dairy feeding.
Feed intake declines under summer conditions (high temperatures and humidity). It is recommended to provide better quality forage to minimize climatic effects. Also, cooling cows by the use of sprinklers and ventilation can reduce body temperatures by 1º-2º C.

General Observations
Liberal feeding of dairy cows is the practice in Israeli daring since the 50's. The aim is to utilize the genetic potential of the animal to the fullest.
The main problems to be dealt with remain:
How to increase intake and energy supply to animals.
How to deal with the problem of digestibility of feeds especially when very good forage is not available or in very short supplies.
How to balance maximum yields with maximum profit.
It seems that simple and properly balanced diets, minimum transfer of cows between groups, with the help of good housing, health control, fertility and breeding are the key to success for any dairy farm.
All rights reserved to ICBA   |   Powered by AKOL Anat Keshev Ltd.