Especially in Western Europe there is a lot of interest in the concept of early feeding of chicks, either during hatching or immediately after hatching. An argument for early feeding is an expected improvement in welfare. The chicks do not have to wait for feed and/or water but have it available as soon as they emerge from the shell, and it is often assumed that if they do not have it available they will suffer from hunger and thirst. How much this is compensated by the presence of the residual yolk is not really known and often not really considered in the discussion.

Besides the assumed benefits on welfare, it is also assumed to give a benefit in production. Better growth, better feed efficiency and lower mortality is often mentioned in this respect, and often used as an argument to support the assumed benefits on welfare.

It is not my intention to give an opinion on the welfare aspects of early feeding as it is not my area of expertise. But if we use data from experiments to prove a point, it is important that we interpret that data in the right way.

In 2017 a group of researchers performed an impressive analysis of all the published data on this subject until that time, for which a total of over 75 peer-reviewed articles was used.
(de Jong IC, van Riel J, Bracke MBM, van den Brand H (2017) A 'meta-analysis' of effects of post-hatch food and water deprivation on development, performance and welfare of chickens. PLoS ONE 12(12))

The article gives a very good analysis of the existing literature, but it’s interesting to see how easily things can be misinterpreted when you do not read carefully.

Table 1 of the article shows an overall analysis of the production results after periods of feed and water deprivation. The authors put non-feed and water deprivation on 100%, and then analyze how much the values change percentage wise after a certain period of feed and water deprivation. The article shows the comparison for body weight, FCR, feed intake and mortality, but I took out only body weight and feed intake. If we look for instance at the first line, if the BW at 7 days with no feed and water deprivation (defined as feed and water within 0 to12 hours after hatch or after pull) is set at 100, then feed and water deprivation for 24 hours (defined as no feed and water for 12 to 36 hours after hatch or after pull) is giving 92.8% of the body weight that you get with direct feeding, and the birds also only eat 92.1% of the feed that the other birds consumed. And it shows clearly that the longer you don’t give feed and water, the lower the body weights and feed intake will be, not only at 7 days but also at 21 and 42 days. And it’s very understandable that people will judge this as a lack of welfare, as the birds do not eat and grow as they should do and are probably suffering.

 Table 1: adapted from de Jong et al, 2017

Different superscript letters in a line indicate significant differences (p<0.001)

But what is reality? If in a practical situation we talk about 7 day body weight, we talk about the body weight 7 days after placement, so after 7 days of eating. In the article cited the 7 day body weight is defined as the body weight 7 days after hatching or pulling. So if we then have 24 hours of no feed and water, we do not measure after 7 days but after 6 days of the birds having access to feed and water. So what would happen if we calculate the relative time that birds can eat, as a percentage of the time that birds eat when they have immediate access to feed and water, and we compare that with the relative body weight and feed intake that they have achieved.

This way of calculating shows that its perhaps not the feed and water deprivation by itself that caused the delayed growth, but simply the fact that the birds had less time to eat. Only in the first 7 days they are actually eating more than what you would expect based on the time calculation (for instance with 24 hours deprivation they have only 85.7% of the time to eat but still eat 92.1% and grow 92.8% of the amount with full availability to feed and water). After 48 hours they have 71.4 % of the time to eat but eat only 67.4% of the maximum amount and grow 83%. The difference between the relative low amount of feed and the amount of growth for this group does not seems totally logical but is perhaps due to the fact that many different sources were used which might confuse some of the information.

But what the table shows is that the percentage of loss in growth and feed intake perhaps doesn't indicate possible consequences of feed and water deprivation on welfare aspects, but shows that when the birds have access to feed and water, also after a period of deprivation, they just catch up with the normal speed of eating and growing. They also do not compensate for the loss of time, as it can be seen especially at 42 days that they simply eat and grow the amount that is related to the number of days they have available for it. And this is perhaps one of the reasons why the picture of welfare issues after feed deprivation is not that well recognized in the field: if the farmer receives the birds they grow depending on the time they have for eating, not on the time they have been without feed and water. Because the farmer considers the moment of placement as starting day, not the moment of hatching or pulling.