Effect of continuous suckling/”ewe-rearing” and supplementation on growth performance of Katahdin lambs and reproductive performance of the ewes. S.L. Rastle-Simpson, K.N. D’Souza, A.K. Redhead, Q. S. Baptiste, M. Knights Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, WV

Traditional Weaning Common management practice 3-4 months of age Reduce metabolic demand on the dam o –BCS to recover o –Earlier resumption of postpartum reproductive cycles Lambs placed into feedlots Psychological and nutritional stress Compromise growth, immune function, and welfare of lambs o –Retardation of growth in lambs up to 6 months of age Leads to overall decline in productivity

Continuous Suckling Lower susceptibility to parasitism o –Reduced worm burden o –Whether continuous suckling can reduce parasitism under field conditions has yet to be determined Increased pre-slaughter growth rates o –Depression in growth rate of early weaned lambs

Markets Increase in demand and price for lighter (<100 lbs.) market lambs in the Northeast. Market weights can potentially be achieved by 3-5 months of age Lambs can be finished on pasture while suckling without being placed in a fattening facility

Objectives Determine the effect of continuous suckling with and without supplementation on the growth rate of lambs Determine reproductive performance of ewes with continuous suckling and weaning

Experimental Design Replicate 1: Fall born lambs 2.5 – 3 months of age. All animals were on dry lot for the entire experiment (3 months) with ad libitum access to 2 nd cutting hay Supplemented lambs received ad libitum access to 16% crude protein lamb pellets Lambs were weighed approximately every two weeks Weaned No supplement Weaned Supplemented Suckling No supplement Suckling Supplemented

Experimental Design Replicate 2: Spring born lambs months of age All animals were on pasture for the entire experiment (3 months) Supplemented lambs received ad libitum access to 16% crude protein lamb pellets Lambs were weighed approximately every two weeks Weaned No supplement Weaned Supplemented Suckling Supplemented Suckling No supplement

Replicate 1Replicate 2MeanP-Value N6493- Birth weight, kg4.3 ± ± ± Age at start, days69.9 ± ± ± Initial weight, kg17.2 ± ± ± Pre-average daily gain, g/day184.2 ± ± ± End weight, kg29.7 ± ± ± Overall weight gain, kg12.5 ± ± ± 0.3NS Overall average daily gain, g/day142.3 ± ± ± 3.2NS Table 1: Growth characteristics of lambs in replicates 1 and Lambs in replicates 1 and 2 were born in Fall (August-September) and Spring (March-April).

Type of Rearing Ration P-value SucklingWeanedSupplement No- Supplement Suckling Status Supplement Age at start, days75.8 ± ± ± ± 1.3NS Initial weight, kg18.8 ± ± ± 0.5NS End weight, kg32.3 ± ± ± ± < Overall weight gain, kg13.4 ± ± ± ± 0.4< Overall average daily gain, g/day ± ± ± ± 4.4< Table 2: Effect of type of rearing and grain supplementation on growth characteristics of lambs 1 1 Data pooled from replicates 1 and 2.

Replicate 1 (Fall)Replicate 2 (Spring)MeanP-Value N3656- Days Post-partum (days)71 ± ± ± Pregnancy Rate 1 (%)75 ± ± ± Percent Lamb (%)73 ± ± ± 4.7NS Prolificacy 2.0 ± ± ± Ram-Lamb Interval (days)153.4 ± ± ± Table 3: Reproductive Performance of ewes in replicates 1 and Ewes in replicates 1 and 2 were bred in Fall (October-November) and Summer (June-July).

SucklingWeanedMeanP-Value Days Post-partum (days)71 ± 1.2 (48)80.7 ± 1.9 (52)76.8 ± 1.26NS Pregnancy Rate (%)65.2 ± 7.1 (46)58.7 ± 7.3 (46)62 ± 4.8NS Percent Lamb (%)68.3 ± 7.3 (41)79.5 ± 6.2 (44)74.1 ± 4.7NS Prolificacy1.6 ± 0.1 (28)1.7 ± 0.1 (34)1.7 ± 0.1NS Ram-Lamb Interval (days)162.6 ± 5.1 (28)167.5 ± 5.1 (34)165.3 ± 3.2NS Table 4: Effect of type of lamb rearing on reproductive performance of ewes 1. Values presented are the mean and standard error with the number of animals available for observation for each variable in parentheses. 1 Data pooled from replicates 1 and 2.

Conclusions Continuous suckling of lambs shows a greater increase in growth characteristics. No decline seen in lambs weaned at any age. Weaning of lambs does increase reproductive performance of ewes. There was no significant difference in pregnancy rate between ewes whose lambs were either continuously suckled or weaned.

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