Supplements Containing Escape Protein Improve Redberry Juniper Intake by Goats

Abstract

Redberry juniper (Juniperus pinchotii Sudw.) is a common invasive plant species in west-central Texas. Goats will consume redberry juniper, but intake is limited by monoterpenoids found in the plant. Previous research has shown that goats will increase juniper intake through 1) conditioning and 2) protein supplementation. This study compared intake of juniper when goats received different protein supplements either with or without protein sources that are high in amino acids that escape digestion in the rumen. Recently weaned Boer-cross goats (n 5 47) were randomly placed into five treatments. Treatments 1, 2, 3, and 4 received a protein supplement and juniper for 1 h daily for 14 d, along with a basal diet of alfalfa pellets (2% body weight). Treatment 5 received only a basal diet of alfalfa pellets and juniper. All supplements were formulated to be isonitrogenous (37% crude protein [CP]). Treatment 1 contained cottonseed meal (high CP escape value), treatment 2 contained cottonseed meal and distiller’s dried grain (higher CP escape value), treatment 3 contained soybean meal (low CP escape value), and treatment 4 contained soybean meal and distiller’s dried grain (moderate CP escape value). Refusals of juniper, supplements, and alfalfa were weighed daily to determine intake. Supplementation with 1) cottonseed meal, 2) soybean meal, or 3) soybean meal and distillers dried grain did not influence (P . 0.05) juniper intake. Conversely, goats supplemented with cottonseed meal and distiller’s dried grain ate more (P , 0.05) juniper than goats receiving only alfalfa, possibly because of increased escape of glucogenic amino acids. We contend that supplementation with feeds high in protein escape values should increase juniper intake on rangelands.