Feeding Camelina Meal To Growing Dairy Heifers

By Jill Anderson

Introduction

A relatively new cruciferous oilseed crop, Camelina sativa is being introduced to South Dakota, Minnesota, North Dakota and Montana. This non-food oilseed is a part of the Brassica family, more common food crops include cabbage, brussel sprouts, cauliflower, kale, rapeseed/canola and broccoli (Moser, 2010). The renewed interest in camelina is in relation to demand for new feedstocks for biofuel production as the oil content of camelina seed is approximately 40%, with 90% of the total oil as polyunsaturated fatty acids (PUFA) (Zubr, 1997). The resulting meal after oil extraction is high in protein (35-40% CP), which could be fed to livestock as a protein supplement. However the anti-nutritional factors such as glucosinolates in camelina limit its inclusion in rations. Currently, federal regulations limit inclusion to 10% of the diet dry matter (DM). Glucosinolates may affect palatability, thyroid function, and growth performance. Feeding camelina to beef cattle did not adversely affect growth or reproduction (Grings et al., 2014). In order to determine the viability of camelina meal as a feedstuff for growing dairy heifers a feeding trial was conducted in the Dairy Science Department at SDSU.

Experiment

The objective of this research was to compare the growth performance, metabolic profile, and nutrient utilization of dairy heifers fed cold-pressed camelina meal (CAM), linseed meal (LIN), or reduced-fat distillers dried grains with solubles (DDGS). From past research we know that DDGS will maintain heifer growth performance, so we used it as the control in this study, while LIN is a protein source similar in composition to CAM without glucosinolates. We hypothesized the highly digestible protein in camelina meal would improve heifer performance. A 12-week randomized complete block design study was conducted using 33 Holstein and 9 Brown Swiss heifers (144.8 ± 22 d of age) with three treatments. Treatments were 10% of the diet as CAM, LIN, or DDGS (DM basis). All diets contained 60% grass hay and 40% concentrate mix. Diets were balanced with corn and soybean meal to be similar in energy and protein content. Diets were individually limit-fed to 2.65% of body weight (BW) using a Calan gate feeding system. Frame sizes, BW, and body condition scores (BCS) were measured on two consecutive days every two weeks. Jugular blood samples were taken at the beginning of the study and then every 4 weeks throughout at 3.5 hours post-feeding for analysis of blood metabolites and metabolic hormones. Rumen fluid samples were taken via esophageal tubing at the same time as blood sampling during week 8 and week 12. Fecal samples were taken during the last week of the study for evaluating total tract digestibility.

Results

Results indicate that heifers fed DDGS had the greatest DMI (Table 1). Heifers fed CAM tended to have decreased average daily gain (ADG) compared to LIN and BW was less for the CAM treatment and greatest for LIN. Gain to feed was similar among treatments. Most body frame measurements and rate of frame size growth were similar among treatments. Body condition scores (on a 1 to 5 scale) were slightly greater for CAM and DDGS compared to LIN. The rumen total volatile fatty acids, acetate: propionate, and pH were similar among treatments with minor shifts in volatile fatty acid profile (data not shown).

Table 1. Growth performance results for dairy heifers fed diets with 10% camelina meal (CAM), reduced-fat DDGS (DDGS) and linseed (LIN).