- RATIONS FOR BEEF
We have looked at the rationing of dairy cows and we have seen that rations are divided into two parts; maintenance rations which are the basic amount of food required to keep the animal alive, and production rations which are fed to animals producing milk. For a milking cow, the ration consists of the maintenance ration plus the production ration, and an efficient dairy farmer feeds the production ration according to the amount of milk each cow is giving. He feeds according to the yield of the cow and this practice avoids under feeding high yielding cows and over feeding low yielding cows.
The feeding of beef animals is similar to the feeding of dairy animals in so far as rations are divided into maintenance and production rations. However, the feeding of beef animals can be divided into the following:
- The feeding of breeding cows both dry and in-milk. In this case the production ration will be fed for milk production which goes to feed the cow’s calf. As this cannot be measured, an estimate of the amount of milk given by the cow each day is made and a ration to cover this milk is fed.
- The feeding of growing steers and heifers that have been weaned. The production of these animals is their growth, the amount of bone, meat and fat that they are producing each day.
- The feeding of fattening animals, either on grass, in paddocks with concentrate feed or in pens with ad lib (as much as they want to eat) high energy feed. Animals that are being fattened for slaughter often have reached the end of their growing period so that their production is some lean meat or muscle and fat. All animals that are sent for slaughter should have a covering of fat over the muscle. The secret of fattening is to make sure they do not get too fat.
The following tables give the daily nutrient requirements for various types of beef cattle. You may recall that in an earlier lecture you were told that the daily dry matter intake of beef animals is 2% of the live-mass of the animal. In fact, this is an average figure, and it applies to beef cows in milk and growing steers and heifers which are putting on the maximum amount of daily live-mass. The tables give the daily dry matter intake for all the classes of beef animals.
ALL THE FIGURES IN THE TABLES ARE ON A DRY MATTER BASIS.
Table 1: Daily Nutrient Requirements for Beef Breeding Cows (N.R.C. 1970)
|Body Mass (kg)||Dry Matter Intake (kg)||CP (kg)||DCP (kg)||TDN (kg)||Ca (g)||P (g)||Vit A I.U. x 1 000|
|Dry Pregnant Cows|
| 9 |
| 9 |
|Lactating Cows, first 3 – 4 months|
If you look at the daily requirements of the dry, pregnant cow weighing 450kg, you can see that she will need 3.4kg of T.D.N., 0.19kg of D.C.P. and that her dry matter intake will be 6.8kg per day. As an example we will consider a ration for this cow in summer and in winter.
Grazing veld in November – December. Looking at the table for veld grass in Lecture 12, grass at this time of the year contains a T.D.N. of 61.7% and a D.C.P. of 4.47. Our cow will satisfy her appetite so that she will consume 6.8kg of dry matter each day and this will contain the following nutrients:
- T.D.N. – 61.7 x 6.8 = 4.19kg 100
- D.C.P. – 4.47 x 6.8 = 0.30kg 100
Compare these figures with the requirements and you can see that she is getting more nutrients than she requires so that she should be in good condition. One point to remember is that veld grass is often low in phosphorus, even in summer, and a common practice is to feed cattle a mixture of calcium phosphate and salt when they are on summer grazing. These two materials are mixed together and put out on the veld in small troughs for the cattle to help themselves. The troughs are placed near the water points so that the cattle can find them easily.
Being a beef cow, our animal will be grazing on the veld in winter, and her requirements will still be 3.4kg of T.D.N. and 0.19kg of D.C.P. a day. However, the composition of the veld has now changed, and looking at the figure for veld grass and veld hay, we will use the following figures for winter veld:
- T.D.N. – 45%;
- D.C.P. – Nil.
The cow on full grazing will still eat 6,8kg of dry matter a day and this will supply:
- T.D.N. – 45 x 6.8 = 3.06kg
- D.C.P. – will be Nil.
It is obvious that the cow is being severely underfed and is getting no protein at all. She will have to be given extra food to supply 0.34kg of T.D.N and 0.19kg of DCP. The normal practice is to supplement cattle on veld in winter with protein licks or blocks, either made on the farm or purchased from one of the cattle feed firms.
These licks contain urea to supply some of the protein, and salt to prevent cattle eating too much of the lick at one time. A lick with a T.D.N. of 70% and a D.C.P. of 30% would be satisfactory, and by doing a simple sum, we can calculate how much the cow would have to eat to supply the nutrients required, particularly the protein.
The block contains 30% of D.C.P. and we want to know how much the animal will have to eat to supply her with 0.19kg of D.C.P. a day. Therefore:
- 30 x X = 0.19
- 30X = 0.19 x 100 = 19
- X = 19 = 0.63kg 30
She will have to eat 0.63kg of the lick to supply 0.19kg of D.C.P. a day.
In addition, the 0.63kg of lick that she eats will supply the following amount of T.D.N.:
- 70 x 0.63 = 0.44kg, which will meet her requirements. 100
We can say that our cow will be kept in good condition by grazing winter veld provided she is supplemented with 0,63kg of a high protein lick or block, with a T.D.N. of 70% and a D.C.P. of 30%.
The next two tables give the nutrient requirements for grazing steers and heifers and for bulls. Provided that you know the weight of the animals you can work out rations to suit your beef cattle at any stage of their growth.
Table 2: Daily Nutrient Requirements for Growing Steers and Heifers (N.R.C. 1970)
Table 3: Daily Nutrient Requirement of Bulls (N.R.C. 1970)
The next table is rather different, and deals with beef cattle that are being fattened in pens on ad lib high-energy diets. The daily dry matter intake of these animals will vary according to the T.D.N. percentage in the ration. The more concentrated the ration the higher the T.D.N. and the higher their daily intake will be. The second part of the table shows the daily carcass gain of the animals at different: levels of T.D.N. in the ration. Again, the higher the T.D.N. (or energy) in the ration the more the animal will eat and the greater will be the daily weight gain. One point to note is that the figures are for carcass gain, as beef animals kill out at half of their daily live-mass gain. An animal putting on a carcass gain of 0.68kg a day will have a live-mass gain of 0.68 x 2 = 1.36kg a day.
Table 4: The T.D.N. Content of Dry Fattening Rations Fed Ad Lib to Beef Steer and their Predicted Daily Dry Matter Intake and Carcass Gain (Carlow and Donking (1975))
AS AN EXAMPLE, A TYPICAL RATION FED TO STEERS IN PENS WOULD BE THE FOLLOWING:
- 360kg of Maize Meal
- 50kg of Beef Concentrate (64% C.P.; 54% D.C.P.)
- 90kg of Milled Veld Hay
This ration would have a T.D.N. of 72% and a D.C.P. of 10%. Feeding such a ration ad lib to steers weighing 350kg live-mass, you would expect the following results:
- Dry Matter Consumption per day 8.40kg
- Carcass Gain per day 0.48kg
- Live-mass Gain per day 0.96kg
RATIONS FOR SHEEP
Rations for sheep can be calculated in exactly the same way as rations for beef cattle, as long as you know their requirements. Obviously these will vary according to the type of the sheep and, if it is an ewe, the stage of production i.e. is she dry, in lamb or suckling a lamb.
Table 5 gives examples of the daily nutrient requirements of sheep at two different weights and various stages during the year. All the figures are in grams.
|Body mass||D.M. Intake||T.D.N.||C.P.||D.C.P.||Ca||P||Salt|
|Ewes that are dry, but in-lamb|
|Ewes that are in-milk, first 8 – 10 weeks of Lactation|
|Ewes in-milk, end of Lactation|
|Table 6: Growing Lambs (figures in grams)|
|Table 7: Fattening Lambs (figures in grams)|
3. RATIONS FOR PIGS AND POULTRY
Although figures are available for the nutrient requirements of pigs and poultry, it is unusual for a commercial farmer to mix special rations for these types of stock. Most farmers buy balanced rations from one of the feed firms and feed these at the rates recommended by the firm.
A common practice of farmers who have maize available on their farms is to buy high protein concentrates which are designed for mixing with maize to produce a balanced ration. A 1 to 1 concentrate would be mixed in the ratio of 1 part maize meal and 1 part concentrate.
A 3:1 concentrate would be mixed in the ratio of 3 parts maize to 1 part concentrate, e.g. 300kg of Maize to 100kg of the concentrate meal.
These concentrate meals are very useful because they contain all the protein, minerals and vitamins to make a properly balanced ration when mixed with maize, and the resulting ration is cheaper than buying the whole ration from the food compounder. It is important to follow the manufacturer’s instructions when it comes to mixing the ration; do not try to economise by mixing more maize in the ration because it will not be balanced – the T.D.N. will be too high and the content of the other nutrients too low.