Written collaboratively by Karla Rodriguez-Hernandez, Mark Berhow and Jill Anderson.
Plants of the Brassicacea family (canola, camelina, carinata) are rich in glucosinolates. Glucosinolates are compounds that by themselves are non-harmful. When degraded during chewing and digestion however, they form substances that cause a bitter taste which affects the preference for the meal, therefore, potentially decreasing the intake of oilseed meals. Additionally, FDA regulations limit inclusion of brassica meals such as carinata and camelina meal to 10% of the diet dry matter for cattle. However, the amount and type of glucosinolates is different among oilseed meals (Table 1). To our knowledge, there is no information about taste preference of different oilseed meals for dairy heifers. Identifying taste preferences of oilseed meals is very valuable to alert dairy producers of possible initial intake issues when these feedstuffs are used in rations. It was hypothesized that as the content and type of glucosinolates varies depending of the oilseed meal, the taste preference could be different, affecting the dry matter intake (DMI) of dairy heifers.
Table 1. Content of glucosinolates in canola, camelina, and carinata meal.
|Item||Glucosinolates (mg/g of DM)|
|* Cold pressed meal. The content of glucosinolates in solvent extracted meals could be different.
To test the hypothesis, a palatability study was conducted in summer of 2016 by the Dairy and Food Science Department at the SDSU Dairy Research and Training Facility (Brookings, SD). For the experiment six Holstein heifers, approximately 6-8 months old, were maintained in individual pens and received five different grain mixes containing 10% of the dry matter intake (DMI) as cold-pressed camelina meal, cold-pressed carinata meal, canola meal, linseed meal (oilseed control with no glucosinolate), or dried distillers grains with solubles (DDGS) (included as non-oilseed control). The remainder of the grain mixes were comprised of similar amounts of ground corn, soybean meal and mineral mix to meet nutrient requirements. Grain mixes were offered to each heifer in a sequential elimination experimental design with four feeding segments. All five grain mixes were offered for 5 days. After the fifth day of data collection, the treatment with the overall greatest consumption (first place preference) was removed and replaced by an empty container. After another 4 days of data collection the treatment with the overall greatest consumption (second place preference) was removed and replaced by an empty container. After another 3 days of collection the treatment with the overall greatest consumption (third place preference) was removed and replaced by an empty container. The last 2 days, the remaining two treatments were used to determine the 4th and 5th place preferences. Each day the location of the feeders was also randomized to avoid any preference or behavior impacts based on location. Hay was offered at 1.6% of the body weight throughout the day. Grain mixes were offered for ad libitum intakes during two 30 minute periods in the morning and evening, and refusals were weighed and recorded daily. Prior to the start of the study heifers were housed in pens for two days to adapt to the surroundings and establish baseline intakes by feeding standard farm grower pellets.
Taste preferences were determined by weighing daily intake amounts. Lesser ranking numbers indicate a greater preference (more consumed) by the heifer. The overall ranking for taste preference of the five grain mixes is shown in Table 2. The DDGS Grain mix was the most preferred by heifers, followed by Linseed meal. Carinata and canola meals were tied for third place with camelina meal as fifth ranked for taste preference by the heifers.
Table 2. Ranking of treatments over all the feeding segments for taste preference*
|*Rank of the treatment diets is given with 1 = most preferred and 5= least preferred.
Results demonstrated that even though carinata meal had the greatest glucosinolates content, it was in the third rank for taste preference and was tied with canola meal, which is already commonly fed in dairy diets. However, producers need to be aware that some heifers may prefer carinata meal more than others and that some dairy heifers, and cattle in general, may initially need an adaptation period to adjust to carinata meal flavor.
- Lawrence, R. and J. Anderson. 12/21/2015. Camelina meal and carinata meal: potential protein sources for dairy cattle.
- Rodriguez-Hernandez, K., J. Anderson, and M. Berhow. 05/16/2016. Ensiling carinata meal with forage: an option to decrease the glucosinolate content.