Feed management: The dilemma of a pre-layer diet

Eggs place a great demand on bone calcium reserves. | Natalyka, Dreamstime.com

Using a pre-layer diet has obvious benefits but might also predispose pullets to kidney failure.

A pre-layer diet is a special formula, rich in calcium, that is being offered to developing pullets during the last couple weeks before they start laying their first eggs. In most cases, this is during the period from the 16th until the 18th week of age. There are many small variations between a developer diet and its follow-up, the pre-layer diet, but in essence, the major difference is the calcium concentration. In fact, many nutritionists use the exact same developer formula, and they just double up the calcium concentration; a very simplistic approach. Whereas a developer diet contains no more than 1 percent calcium, a pre-layer diet can contain anything between 2 and 2.5 percent calcium.

The reasoning behind this calcium flush is that the medullary bone structure develops rapidly after the 15th week of age. Thus, the late developing phase is ideal to maximize bone calcification. This is in anticipation of providing the pullets with sufficient calcium during the onset of the laying period. After all, bone calcium deposits are key in eggshell formation during the daily calcium cycle of layers. As it happens, without such calcium loading, the earlier-maturing pullets will produce two to three eggs before stopping to replace bone calcium reserves, only to repeat the same process again and again when they are capable of having clutches of 30-40 eggs before the first stop.

The negative side of the practice of offering pullets a calcium rich pre-layer diet is that kidneys are burdened too early with high calcium levels, which can lead to kidney problems later on when hens will be aged and have to cope with layer diets containing up to 4 percent calcium. Some nutritionists also suggest a faster drop in calcium absorption efficiency with age when pullets are started too early on high-calcium intake. In addition, if we account for the usual three pullet diets already being used during the rearing phase, having a fourth diet just for one to two weeks is not always welcomed from a logistics point of view.

In essence, pullet growers have to decide between having a number of earlier-maturing pullets starting to lay eggs before their time and using insufficient bone reserves (and thus entering the layer house with depleted bone reserves) or risk kidney overload and handling a fourth diet. As it happens, this is a decision taken after accounting for the specific strain of genetics being used and the time pullets actually enter the layer house. To this end, there are four schools of thought:

1. Use a dedicated pre-layer formula

This is the typical approach recommended by most genetic stock suppliers and applied by many integrated poultry producers. The usual time is two weeks before entering the layer house, but this might be reduced according to individual farm circumstances and genetics being used.

2. Do not use a pre-layer diet

This is a “do-nothing” approach as advocated by those who had bad experiences with kidney problems in pullets and with some pullet growers that want to minimize cost of production, especially if they are not connected with layer productivity. If you decide to follow this approach, it is best to consult with your genetics supplier and discuss it with all prospective buyers of the pullets.

3. Use the layer diet

Those who want to avoid handling a fourth pullet diet often use the first layer diet, which contains 3 to 4 percent calcium. This might be a convenient approach, but it is rather costly and even riskier than a 2 percent calcium pre-layer diet. It is being used only in very small operations and only for a few days before moving to the layer house. Nevertheless, some nutritionists use this approach even in large operations with some success depending on the duration of the feeding.

4. Synchronize egg laying with layer diet feeding

Those against using a calcium-rich pre-layer diet advocate better matching animal needs with diets offered. This entails a high uniformity in body weight and composition for the entire flock, through management, that enables a large number of pullets to start laying their first eggs during a very short period of time. As such, they can be moved at the layer house at the exact needed time and switched on to the correct layer diet. It is obvious this method requires deep knowledge of the specific genetics being used at the specific farm and also a close monitoring and continuous adjustment of flock growth patterns.

In brief

As we can only feed the "average" bird, we cannot avoid overfeeding the least productive animals and underfeeding the most efficient ones. We can move either side of the equation, but we will end up wasting nutrients (cost) or sacrifice performance (profitability). At the end, it is a decision of balancing available information based on actual animal performance, but this requires close monitoring of each flock by dedicated and well-trained staff. In my opinion, a pre-layer diet is usually worth the risk, expense and logistics hassle, but it must be done in moderation and in a very precise manner.