Date of Graduation


Document Type


Degree Type



Davis College of Agriculture, Natural Resources and Design


Animal and Nutritional Sciences

Committee Chair

Scott A Bowdridge

Committee Co-Chair

David P Belesky

Committee Member

Eugene E Felton


Controlling gastrointestinal nematode infection of sheep has become a challenge resulting from reduced anthelmintic efficacy. Previous data have indicated that grazing lambs supplemented with a 16% CP ration at 1% BW maintained growth comparable to lambs given anthelmintic despite greater infection. Thus the objective of the following studies was to determine the effects of bypass protein on fecal egg count reduction and post weaning growth in parasitized, grazing lambs. Experiment one utilized spring-born Suffolk crossbred lambs separated into 3 supplement groups: alfalfa pellets (AFP) (15% CP), corn and soybean meal (CSM) (19% CP) and corn, soybean meal and fish meal (CFM) (19% CP). All animals were supplemented at 1% average body weight (BW) except AFP animals which were supplemented at 1.28% average BW to account for lower supplemental CP. Animals were grazed on small paddocks for a maximum of 3 days. Fecal egg count (FEC) was significantly lower for the AFP and CFM animals compared to CSM supplemented lambs. FAMACHA scores were reduced by 1.3 in CFM lambs. Average daily gain (ADG) was also significantly affected as lambs supplemented with CFM was significantly higher than gain of lambs receiving AFP; with CSM being intermediate. Fish meal is known to have higher oil content, and perhaps lower FEC was a result of oil differences. To test this hypothesis, January-born Suffolk and Dorset lambs were randomly assigned to one of three treatment groups: corn and soybean meal (CSM), corn, soybean and fish meal (CFM) and corn, soybean meal and fish oil (CFO) all at 19% CP. Animals were supplemented at 1% average BW. Animals were kept in a raised floor barn during a transition period where they were trickle infected with Haemonchus contortus larvae. After the transition period animals were moved to pasture where they grazed small paddocks for 3 days. FEC resulted in a tendency (P = 0.1103) for differences between groups. Further pairwise comparisons indicated that FEC of CFM supplemented lambs was lower than CSM but not different than CFO. Packed cell volume (PCV) was significantly higher for the CFO animals although all groups were within a normal range. No differences in gain were observed. These data indicate that supplementing grazing lambs with a rumen bypass protein source (CFM) has the potential to reduce FEC while maintaining acceptable gain on pasture.