Almond hulls and shells as an alternative fiber source in limit-fed growing beef cattle diets

Almond hulls and shells are a by-product of almond production that can be incorporated as a feed ingredient in beef cattle diets. Three experiments were conducted to determine the effects of hammermill screen size on almond hull and shell bulk density and inclusion of ground or non-ground almond hulls and shells in limit-fed growing diets on growth performance, diet digestibility, and ruminal fermentation characteristics of beef cattle. In experiment 1, almond hulls and shells were ground with a laboratory-scale hammermill using no screen, a 11.1-mm screen, a 19.1-mm screen, or a 25.4-mm screen. Each screen-size treatment was ground at three separate time points (n= 3 replications/treatment). Grinding almond hulls and shells with no screen increased bulk density by 111% and minimized proportions of fine particles; therefore, almond hulls and shells ground using no screen were included as a treatment in the following experiments. In experiment 2, 364 steers (initial body weight [BW]: 257 +/- 20.7 kg) were blocked by truckload (n = 4), stratified by BW, and assigned to pen within block. Pens were randomly assigned to 1 of 4 experimental diets (n= 10 pens/treatment). The control diet (CON) contained (DM basis) 39.5% dry-rolled corn, 7.5% supplement, 40% wet-corn gluten feed, and 13% prairie hay. Non-ground (13AH) or ground (13GAH) almond hulls and shells replaced prairie hay and were fed at 13% of diet DM or non-ground almond hulls and shells were fed at 26% of diet DM and replaced 13% prairie hay and 13% dry-rolled corn (26AH). Diets were limit-fed at 2.2% of BW daily (DM basis) for 56 d. Overall average daily gains (ADG) were greater (P <= 0.05) for CON, 13AH, and 13GAH compared with 26AH. In addition, ADG from days 14 to 56 were greater (P= 0.03) for 13GAH and tended to be greater (P = 0.09) for 13AH compared with CON. Experiment 3 was a 4 x 4 replicated Latin square in which 8 ruminally cannulated heifers (initial BW = 378 +/- 44.0 kg) were fed diets from experiment 2. Apparent dry matter digestibility did not differ (P = 0.21) among treatments. Total ruminal volatile fatty acid concentrations were greater (P <= 0.03) for 13GAH and 13AH compared with 26AH and tended (P = 0.06) to be greater for 13GAH compared with CON. Overall, almond hulls and shells can be utilized as an alternative to prairie hay in limit-fed growing diets without negatively influencing rates of gain or diet digestibility. We evaluated the effects of feeding almond hulls and shells as an alternative to dry-rolled corn or prairie hay in growing beef cattle diets. We determined that almond hulls and shells can be used as an alternative to prairie hay in limit-fed growing diets without negativity influencing growth performance or diet digestibility. The California Almond Industry produces large volumes of almond hulls and shells that can be fed to beef and dairy cattle; however, literature evaluating incorporation of almond hulls and shells into beef cattle diets is lacking. We evaluated the effects of feeding ground or non-ground almond hulls and shells on growth performance, apparent diet digestibility, and ruminal fermentation characteristics in limit-fed growing calves. Replacing prairie hay with ground or non-ground almond hulls and shells at 13% of diet dry matter resulted in similar final body weights, average daily gain, gain-to-feed, and apparent diet digestibility. Conversely, growth performance, ruminal volatile fatty acid concentrations, and ruminal ammonia concentrations were reduced when non-ground almond hulls and shells replaced 13% prairie hay and 13% dry-rolled corn (dry matter basis). Overall, these data demonstrate that ground or non-ground almond hulls and shells can be used as an alternative to prairie hay in limit-fed growing diets.