The effects of continuous-suckling and supplementation on growth performance of crossbred Katahdin lambs (Birth weight 4.2 ± 0.2 kg) were investigated. Lambs (n =68; 17.2 ± 1.0 kg) were randomly assigned within birth- type to be weaned at approximately 75d or to continuously suckle ewes. All lambs were given ad libitum access to hay, and half of the lambs in each rearing method were randomly assigned to be supplemented (10% crude protein, 3.5 % crude fat lamb pellet) ad libitum (weaned + supplemented, WS (n =16); suckling + supplemented, SS (n=17) or received no further treatment (weaned + no supplementation, WNS (n=18); suckling + no supplementation, SNS (n=17). All lambs were weighed at birth, at the initiation of the trial and at approximately biweekly intervals for another three (3) months. Average daily gain (ADG) during the pretrial period (~ 75 days) did not differ among treatment groups (0.18 ± 0.01 kg/d). The ADG during the trial period was higher (P < 0.001) in supplemented (WS, 0.22 ± 0.01 kg/d; SS, 0.24 ± 0.01 kg/d) than in un-supplemented (WNS, 0.06 ± 0.01 kg/d; SNS, 0.05 ± 0.01 kg/d) lambs. Among supplemented lambs, there was a tendency (P =0.1) for higher growth rates in continuous suckled than in weaned lambs. Average final weights were higher (P < 0.001) in supplemented (WS, 36.2 ± 1.36 kg; SS, 40.2 ± 1.36 kg) compared to un-supplemented groups (WNS, 21.7 ± 1.36 kg; SNS, 20.6 ± 1.36 kg). Final weights were higher in the SS lambs compared to lambs in all other groups. The results of the current study indicate that supplementation of lambs increases total ADG and end-weight. Furthermore, continuous suckling along with supplementation results in the highest ADG and end weights. Introduction Materials and Methods  Summer born, crossbred Katahdin lambs, average 75 days of age, were used in this experiment.  All groups were maintained on dry lots for the duration of this study due to time of year; they all received ad libitum access to hay and water.  Lambs were randomly assigned to be either weaned or remain suckling and half of each primary treatment (weaned or suckling) were given ad libitum supplement (10% crude protein, 3.5 % crude fat lamb pellet).  Lambs were weighed at birth, at start of trial and approximately every two weeks for 3 months.  Data was analyzed using ANOVA. Experimental units were;  Weaned or Suckling and supplemented or not supplemented.  Lambs in each group for growth performance. Results Conclusions Abstract Lambs reared with the conventional weaning method may be subjected to stresses that may affect their growth. Weaning has been associated with psychological and nutritional stresses on the lamb resulting in decreased growth rate for up to two months post weaning. The results of the current study indicate that feeding supplements results in increased total ADG and end-weight in both the weaned and continuous suckling groups. In addition, continuous suckling along with supplementation results in the highest ADG and end weights. Figure 2. ADG of lambs over treatment period. 1 period=14-21 days. Figure 1. Treatment groups Weaning, the physical and physiological separation of the dam from her offspring, is a common management practice among lamb producers. Weaning has been associated with psychological and nutritional stress on the lamb that may compromise health and well-being, growth, and increase mortality in the weaned offspring resulting in an overall decline in productivity. However, weaning prior to slaughter may not be necessary as there is an increasing demand for younger lambs at lighter slaughter weights with minimal finish. In some studies, continuous suckling has been shown to increase pre-slaughter growth rates of lambs. Higher growth rates have been observed in late-weaned and un- weaned lambs. The study further examined the impact of continuous suckling on growth rate and potential interactions with type of diet. Weaned, not Supplemented Weaned, Supplemented Suckling, not Supplemented Suckling, Supplemented This project supported in part by the Northeast Sustainable Agriculture Research and Education (SARE) program. SARE is a program of the National Institute of Food and Agriculture, U.S. Department of Agriculture." Figure 3. Average end weight of the 4 treatment groups Figure 4. Comparison of ADG among treatments Effect of continuous suckling/“ewe-rearing” and supplementation on growth performance of Katahdin lambs S.L. Simpson, K.N. D’Souza, Q. S. Baptiste, M. Knights Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, WV