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 2nd cutting hay

• Supplemented lambs received ad libitum access to 16% crude protein lamb pellets

• Lambs were weighed approximately every two weeks

WeanedNo supplement

WeanedSupplemented

SucklingNo supplement

SucklingSupplemented

Experimental Design• Replicate 2:• Spring born lambs 2.5-3 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

WeanedNo supplement

WeanedSupplemented

SucklingSupplemented

SucklingNo supplement

  Replicate 1

Replicate 2 Mean P-Value

N 64 93 -  

Birth weight, kg 4.3 ± 0.1 3.7 ± 0.1 3.9 ± 0.07 0.0001

Age at start, days 69.9 ± 1.4 82.4 ± 1.2 77.3 ± 6.2 0.0001

Initial weight, kg 17.2 ± 0.6 20.4 ± 0.5 19.1 ± 0.4 0.0001

Pre-average daily gain, g/day

184.2 ± 5.5

202 ± 4.6 194.7 ± 3.5 0.0141

End weight, kg 29.7 ± 0.7 32.9 ± 0.6 31.4 ± 0.5 0.0011

Overall weight gain, kg 12.5 ± 0.4 12.3 ± 0.4 12.2 ± 0.3 NS

Overall average daily gain, g/day

142.3 ± 4.9 138.6 ± 4.2 138.4 ± 3.2 NS

Table 1: Growth characteristics of lambs in replicates 1 and 21

1 Lambs in replicates 1 and 2 were born in Fall (August-September) and Spring (March-April).

  Type of Rearing Ration P-value

  Suckling Weaned Supplement No-Supplement

Suckling Status

Supplement

Age at start, days 75.8 ± 1.3 76.6 ± 1.3 77.5 ± 1.4 74.8 ± 1.3 NS NS

Initial weight, kg 18.8 ± 0.5 18.8 ± 0.5 18.8 ± 0.6 18.8 ± 0.5 NS NS

End weight, kg 32.3 ± 0.7 30.3 ± 0.7 35.7 ± 0.7 26.8 ± 0.7 0.04 < 0.0001

Overall weight gain, kg

13.4 ± 0.4 11.5 ± 0.4 17 ± 0.4 7.8 ± 0.4 < 0.0001 < 0.0001

Overall average daily gain, g/day

151.3 ± 4.5

129.6 ± 4.6

192.5 ± 4.7 88.4 ± 4.4 < 0.0001 < 0.0001

Table 2: Effect of type of rearing and grain supplementation on growth characteristics of lambs1

1 Data pooled from replicates 1 and 2.

         

  Replicate 1 (Fall)

Replicate 2 (Spring)

Mean P-Value

N 36 56 -  

Days Post-partum (days)

71 ± 1.2 80.7 ± 1.9 76.8 ± 1.26 0.0003

Pregnancy Rate1(%) 75 ± 7.3 53.6 ± 6.7 62 ± 4.8 0.0374

Percent Lamb (%) 73 ± 7.4 75 ± 6.3 74.1 ± 4.7 NS

Prolificacy 2.0 ± 0.2 1.4 ± 0.1 1.7 ± 0.1 0.0011

Ram-Lamb Interval (days)

153.4 ± 2.9 174.4 ± 6.4 165.3 ± 3.2 0.019

Table 3: Reproductive Performance of ewes in replicates 1 and 21

1 Ewes in replicates 1 and 2 were bred in Fall (October-November) and Summer (June-July).

         

  Suckling Weaned Mean P-Value

Days Post-partum (days)

71 ± 1.2 (48) 80.7 ± 1.9 (52) 76.8 ± 1.26 NS

Pregnancy Rate (%) 65.2 ± 7.1 (46) 58.7 ± 7.3 (46) 62 ± 4.8 NS

Percent Lamb (%) 68.3 ± 7.3 (41) 79.5 ± 6.2 (44) 74.1 ± 4.7 NS

Prolificacy 1.6 ± 0.1 (28) 1.7 ± 0.1 (34) 1.7 ± 0.1 NS

Ram-Lamb Interval (days)

162.6 ± 5.1 (28) 167.5 ± 5.1 (34) 165.3 ± 3.2 NS

Table 4: Effect of type of lamb rearing on reproductive performance of ewes1 . 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.

Stephanie SimpsonEmail:slsimpson@hsc.wvu.e

duPhone: 304-680-4121

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