Yield, nutritional quality, and fatty acid content of organic winter rye (Secale cereale) and winter wheat (Triticum aestivum) forages under cattle (Bos taurus) grazing conditions

Abstract

The objective of this study was to assess yield, nutritional quality, and fatty acid compositions of winter rye (Secale cereale) and winter wheat (Triticum aestivum) forages for grazing cattle (Bos taurus) in an organic system. The rye and wheat were established on two 4 ha plots in September 2015. Six groups of dairy steers rotationally grazed rye (n = 3) or wheat (n = 3) plots divided into seven paddocks (n = 14) from April to June 2016. Forage samples (n = 96) taken prior to paddock grazing were used to analyze forage characteristics. Mixed models with fixed factors of forage, date, and their interaction, a random subject factor of group nested in paddock, and a repeated effect of date were used for each outcome. The linear effect of date on fatty acids was obtained by substituting date as a continuous variable. The mean forage yield for rye was greater (P < 0.05) than wheat (mean {+/-} standard error; 2840 and 2571 {+/-} 82 kg ha-1, respectively). However, rye yielded less in the latter part of the grazing period. Wheat (19.3 {+/-} 0.30% DM) had greater (P < 0.001) crude protein than rye (17.6 {+/-} 0.30% DM). In general, crude protein, digestibility, and minerals decreased during the grazing period. Wheat (66.3 {+/-} 0.54 g 100g-1) had greater (P < 0.001) alpha-linolenic acid (18:3n-3) concentration than rye (63.3 {+/-} 0.54 g 100g-1). Although both forages decreased (P < 0.05) in alpha-linolenic acid concentration, wheat decreased 2.49 times more (P < 0.001) per d compared to rye forage. Winter rye and winter wheat forages are viable for cattle grazing. Producers should initiate early grazing to maximize protein, digestibility, and alpha-linolenic acid intake while the forages are immature.