Strategies to control piglet weight variability in the nursery (2/2): Feeding and feeding

Various strategies are discussed: offering up to 3 different types of feed, budget feeding, density of piglets per feeder space, ...

Controlling and reducing dispersion of live weight during the pig production cycle is one of the biggest challenges farmers and technicians face today.

Strategies to control piglet weight variability in the nursery (2/2): Feeding and feeding troughs

This article and the previous one focus on the management and production measures we can apply in the nursery phase to reduce this dispersion. Our previous article dealt with the impact of weight segregation on dispersion, and the importance of animal comfort. This article will discuss some key aspects of feed management and the importance of feeding trough space.

Key aspects of feeding

The use of highly digestible feed, with guaranteed raw materials, rich in dairy products (caseinates, skimmed milk, whey) and high quality, is one of the strategies designed to improve the adaptation of all piglets to post-weaning (and especially the smaller ones). Aspects such as feed palatability, help to encourage the voluntary intake at weaning and favour a faster maturation of the GI tract, thus helping reduce live weight (LW) variability. A presentation in pellets would be preferable to meal feed and, as per way of administration, it is usually dry. In some cases, delivering gruel feed several times a day and encouraging consumption of water can be of great help to give piglets a good start. Similarly, the development of "nuclei" (defined as a synergistic combination of additives) and more accurate nutritional programs to maximize consumption, digestibility and intestinal health, constitutes the main goal for several animal feed manufacturers.

Nevertheless, feed management is as important as its composition; adapting the type of feed to the age and weight of the animals will help better control LW dispersion and will optimize the use of the diet. We must not relinquish, in this phase, the option to offer up to 3 different feeds (different names are used, so it is better to refer to them as feed 1, 2 and 3) and change gradually from one to another, logistics permitting.

An important recommendation is to work with global feeding programs for the whole nursery period, rather than resort to individual feeds from different sources. Another point to discuss would be "budget feeding", i.e., deciding beforehand the amount of each feed administered per piglet. This would lead to feed changes being carried out for batches of contemporary piglets at different ages, depending on their individual intakes. Smaller piglets are expected to eat feeds 1 and 2 for longer, thereby promoting their start up and growth. Of course, if piglets from the same batch are transferred to the growing and finishing facilities on a fixed day, the smaller ones will eat feed 3 during a lesser number of days. This "budget" system should reduce LW variability in the batch at the end of nursery, although it is sometimes difficult to implement on commercial terms for strictly logistical reasons.

For example, as a general guide, Table 1 summarizes the ​​"target" values to register for the Spanish average conditions in a nursery period of six weeks with piglets weaned at 21 days. There is no doubt that both the animals genetic potential and their health status, as well as management conditions, may increase or decrease the expected values. However, it is important to note that the recommended values for the first week (week 4) are possibly the most contentious, given that the starting period is precisely the time when more importance is awarded to achieving a good balance between growth performance and digestive balance.

Table 1. Target values in a standard nursery under current Spanish conditions. An average live weight of 6.2 kg is assumed for piglets at weaning.

	PHASE 1	PHASE 2	PHASE 3	PHASE 4
Weeks of life	Week 4	Week 5-6	Week 7-9	Week 4-9
Final LW (kg)	7.25	11.45	20.10	14.95
Growth (g/d)	150	300	410	331
Intake (g/d)	225	450	720	548
FCR (g/g)	1.50	1.50	1.80	1.65
Total intake  (kg)	1575	6300	15120	22995

The role of space and type of feeding trough

Ensuring that all pigs in the batch or pen have adequate access to feed helps increase consumption and favours a decrease in weight dispersion. Results from our own group (Solà-Oriol et al., 2015) suggest that feeding trough space (defined as the number of piglets / space, according to the type of feeder and density of animals) has a significant effect on coefficient of variation (CV) reduction of up to 12% in animals with access to a feeder that allows a lower density of pigs per space (2.2 piglets / mouth for 5-space feeders vs. 5.5 piglets / space for 2-space feeders). This trial assessed the answer to these two different types of feeders in two groups of animals with the same initial LW and CV at the end of the nursery phase, start of fattening and up to slaughter.

Piglets that were allocated to the 5-space feeder tended to have a higher LW and feed intake compared to the animals assigned to the 2-space feeder (Table 2.) The specific study was conducted with 64-day-old piglets through to the age of 92 days, and suggests that such a strategy could have the same or a similar effect during the nursery phase. The number of spaces is generally high in the nursery phase, partly because densities in the pens are usually higher, and it is very important to ensure that all piglets have proper access to feed. Similarly, the type of feeder (and its proper adjustment) may also have some relevance, especially at the start.

Table 2. Summary of body weight (BW) and average daily consumption (ADC) depending on the type of feeder assigned from 64 to 92 days of life (Solà-Oriol et al., 2015).

Item	2-space feeder	5-space feeder	p-value*
LW (Kg)	32.5	33.1	0.061
ADC (g/d)	562	583	0.062

*Statistical significance set at p <0.05

In short, these few proposals —in general, and due to their highly practical character— should be useful to help maximize homogeneity amongst piglets in the nursery. Similarly, the implementation of a strategy does not necessarily exclude others. In fact, it is advisable, in many cases, to choose more than one, depending on each farm, in order to reduce LW variability and increase the overall efficiency of the productive system.