One of the main objectives of dairy calf management during the milk-feeding stage is encouraging solid feed intake, as growth and development of the rumen is stimulated by the fermentation of solid feed. It is likewise vitally important that young calves ingest sufficient amounts of solid feed in order for a smooth weaning transition to occur, without a growth check. Studies of feed intake preference conducted over the last 30 to 40 years have found that several factors influence preferences including physical properties, taste or palatability, and chemical signals. Indeed, there are multiple feedback signals that control feeding behaviour, including physical ones. Nonetheless, as palatability is a part of this complex equation, it’s recommended by many that taste preferences be taken into account when formulating starter feeds. While a good deal of research has been done in the past on the use of flavour additives to increase palatability, few studies have evaluated calves’ preferences for the actual feed types commonly used in formulating starter rations. With this in mind, a study by the University of Guelph, IRTA Spain, Lucta Spain, and the Catalan Institute for Research and Advanced Studies sought to do just that.
In the study, 500 newly weaned dairy calves that had been offered water and pelleted starter ad libitum from birth, as well as 4 L/d of milk replacer, were fully weaned at day 62 and were tested for preferences for various feed types at 3 and 5 days, post weaning. Important to note is that the starter feed they were given prior to the experiment included 12 varied ingredients so that calves had minimal exposure to any individual feed type. The calves were given 6-hour pairwise preference tests of high-energy and high-protein feed types and were then tested using 50:50 mixtures of the highest and lowest ranked high-protein and high-energy feeds. All tests were designed so that the preferences exhibited could be ascribed to taste and palatability. Additionally, each pairwise test was repeated with 20 calves, to increase the power of the test, and to detect slight variations. The objective was to assess preferences in recently weaned calves for the feed types commonly used in starter rations and to see if those preferences persisted, even after they were mixed with another feed type in ration formulation.
Clear preferences emerged
In the high-energy feed type tests, wheat meal was the highest ranked while corn gluten feed (CGF) ranked lowest. Indeed, calves consumed an average of 448.8 grams of wheat meal compared to only 121.5 grams of CGF during the test. In the high-protein feed type tests, soybean meal (SBM) was the highest ranked feed, while corn gluten meal (CGM) ranked lowest. This clear preference can be seen in the fact that calves consumed 605.1 grams of SBM compared to just 30.0 grams of CGM during the test.
The third experiment took the results from both the high-energy feed test and the high-protein feed test and sought to determine if the calves’ ingredient preferences continued, even when combined 50:50 with other ingredients. As one might expect, the combination of the two highest ranking high-energy and high-protein feeds (wheat meal and SBM) was highest ranked (calves consumed 515.8 grams on average), and the combination of the two lowest ranking high-energy and high-protein feeds (CGF and CGM) ranked lowest (calves consumed 57.2 grams on average). The mixtures containing one highest ranked and one lowest ranked feed ingredient (wheat meal + CGM and SBM + CGF) rated equally, below the highest ranking combination but above the lowest ranking combination. Thus, preferences in the ranking of mixtures was consistent with the ranking of individual ingredients.
It seems clear that in the short term, calves have distinct preferences for certain feed ingredients. And, as palatability of solid feed intake is a part of the complex equation leading to proper intake and the resulting rumen development, consideration could be given to such ingredients when formulating starter rations. Adding these highly palatable energy and protein sources may help to minimize the possible negative effects of less palatable ingredients. But, possible linkage between short-term preferences and long-term intakes has not been studied yet. Therefore, it remains to be seen if palatability leads to greater intakes in the long run. Stay tuned…