sensitive to smell and love sweet flavours. Mixing fresh fruity flavours through the feed stimulates their curiosity, increases their interest in solid feed and encourages them to try it. By triggering further feed intake, flavoured feed promotes a smooth transition from liquids to solids. To determine to which extent flavours stimulate exploratory behaviour in piglets, trials were carried out (see Figure 2). Confirming those results, a series of three trials was per- formed on weaning piglets at a pig farm in Jifa, Shaanxi prov- ince, China, early in 2017 to compare their behaviour when fed with raspberry-flavoured feed (by Pancosma) versus a more common milk-flavoured feed, sold on the Chinese mar- ket. In the first phase, the piglets’ respective interest in both flavours was evaluated while the second and third phases provided results for intake and performance (see Box). The trials determined that raspberry flavour increased piglet feed intake and improved performance. That can be ex- plained by the fact that fruity flavours contain molecules that are generally more volatile than the heavier ones used in milky flavours. The raspberry smell spreads more easily into the air, attracting the animals’ interest first. Flavours with more volatile molecules can provide incentive to encourage exploratory behaviour in piglets. Raspberry flavour improves feed intake compared to milk-flavoured feed in both free-choice trials and imposed- choice trials. The

higher feed intake obtained with the raspberry flavour leads to better performance of the piglets, with higher body weight gain as well as higher final body weight.

Three trials confirm: Piglets prefer raspberry

A first preference trial was performed on 40 weaned piglets, ran- domly allocated to four pens of 10 piglets. The animals were weaned at 21–23 days and weighed 6–7 kg. They were given free access to two different feeds: one containing milk flavour and the other raspberry fla- vour, both dosed at 300 g/tonne. During the four-day trial, the number of contacts between piglets and each feed were counted every five minutes over a 20-minute period. Results showed significantly more contacts with the raspberry- flavoured treatment than with the milk-flavoured one throughout the 20-minute periods and from day to day. While exploratory behaviour was constant for the milk-flavoured feed throughout the trial, the number of contacts increased each day for the treatment with raspberry flavour. A second trial was set up to confirm the hypothesis that increasing piglets’ exploratory behaviour would increase feed intake. The set-up was similar to the first preference trial: 40 animals randomly allocated to four pens. During the seven-day free-choice trial, animals had access to the same feed choices as for the first trial. Piglets were fed ad libitum and water was freely available. Daily feed intake was weighed and recorded per treatment and per pen. Feed intake followed the same trend as preference in the previous trial: intake was higher for the raspberry-flavoured feed than for the milk-flavoured feed.

Intake also increased throughout the trial, in line with previous obser- vations; that is, piglets became increasingly curious about the raspber- ry flavour. The results are consistent with the first trial regarding pref- erence, and they validate the hypothesis that stimulating exploratory behaviour is a good way to increase feed intake. A third trial was performed to validate the effect of higher intake on piglet performance. During the 14-day trial, an imposed-choice set-up of 96 piglets were randomly divided into two groups, with each group having access to only one feed (either milk-flavoured or raspberry-fla- voured). Each group was then subdivided into four different pens of 12 animals each. The researchers recorded the piglets’ initial and final weights; they measured feed intake and average daily weight gain and calculated feed conversion ratio (FCR). Results on feed intake were similar to the previous free-choice trial: average cumulated feed intake was higher for the raspberry-flavoured feed than for the milk-flavoured feed. Piglets once again showed a preference for the raspberry-fla- voured feed with an improvement in feed consumption. This significantly higher feed intake was associated with a significantly higher average body weight gain and a significantly higher final body weight in the case of raspberry-flavoured feed. FCR was statistically improved with the raspberry-flavoured feed.

References available upon request. ▶ PIG PROGRESS | Volume 37, No. 7, 2021 31

Piglets are curi- ous, highly sen- sitive to smell and love sweet flavours.


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