Effect of Continuous Suckling/”Ewe-rearing” on Growth and Level of Parasitism of Lambs and on Productivity and Profitability of Lamb Operations

Final Report for GNE11-029

Project Type: Graduate Student
Funds awarded in 2011: $14,741.00
Projected End Date: 12/31/2013
Grant Recipient: West Virginia University
Region: Northeast
State: West Virginia
Graduate Student:
Faculty Advisor:
Marlon Knights
West Virginia University
Faculty Advisor:
Dr. Doolarie Singh-Knights, Ph.D.
West Virginia University
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Project Information

Summary:

The purpose of this project was to evaluate the effect of continuous suckling (CS)/“ewe-rearing” on growth, intestinal parasitism, and productivity and profitability of sheep production in Appalachia. Weaning at approximately 3-4 months of age is routinely practiced by most lamb producers. One reason weaning is practiced is so that lambs can be placed into feedlots and grown and fattened to reach market weight and condition. 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. Additionally, an increase in the demand and price for lighter (< 100 lbs) market lambs in the Northeastern United States, suggests that market weights can potentially be achieved by 3-5 months of age without a requirement for finishing lambs in feedlots. Lambs for this market can be finished on pasture while still suckling their dams, and in so doing, avoid the stress of weaning and subsequent effects on the health and growth of the lambs. The current study evaluated the impact of CS with and without supplementation with grain on growth performance and level of parasitism in lambs and body conditions score (BCS) in dams. The results of this study indicated that continuous suckling/“ewe-rearing” increased average daily gain and results in a greater total weight gain of 5 kg (11lbs) without any detrimental effects on weight and body condition scores of ewes. Partial budget analysis indicates that producers who implemented this practice achieved an increase in profit of approximately $25 per lamb sold (16-24 percent increase). Further, producers who were exposed to the trials are likely to continue to implement the practice. We conclude that continuous suckling/“ewe-rearing” is a sustainable, low cost management practice that should be recommended to sheep producers in the Northeast USA.

Introduction:

Weaning (separation of the juveniles from their dams) at approximately 3-4 months of age is routinely practiced by many lamb producers. Several reasons have been advanced for weaning of lambs,including inducing a more rapid transition to a cheaper forage-based diet by enhancing rate of development of the rumen. Additionally, early weaning is thought to reduce the metabolic demand on the dam, all owing her body condition score to recover prior to the next breeding season. Further, weaning removes the suckling stimulus, it has been suggested that this may facilitate an earlier resumption of post partum reproductive cycles and the potential for accelerated re-breeding of dams. Weaning is also routinely practiced so that lambs can be placed into feed lots and grown and fattened to reach market weight and condition.

 

However, weaning has been associated with psychological and nutritional stress on the lamb that might compromise the growth, immune function, and welfare of the young animal resulting in an overall decline in productivity. In some studies, continuous suckling has been shown to lower susceptibility to parasitism and increase pre-slaughter growth rates of lambs. Worm burden has been shown to be reduced in young lambs consuming milk compared to their counterparts on dry-feed. Higher growth rates have been observed in late-weaned and un-weaned lambs. The proposed study will further examine the impact of continuous suckling on growth rate and potential interactions with type of diet.

 

Continuous suckling may well increase growth rate of lambs. Higher growth rates have been observed in late-weaned and un-weaned lambs in previous work by Knights et al. (2012). In a series of experiments evaluating the effect of time of weaning on subsequent growth rate of hair-sheep lambs, Knights et al. (2012) observed higher growth rates and final   weights in late (5 to 6 months) compared to early-weaned (2.5 to 4 months) lambs. Early-weaned lambs consistently showed a depression in growth rate which lasted for almost 2 months. Interestingly, higher growth rates and market weights were observed in un-weaned (continuous suckling), hair-sheep lambs compared to weaned when given ad libitum access to forage and concentrate, irrespective of the age at weaning (Knights et al., 2012). However, this study did not include treatment groups in which lambs were given access to all forage diets.

 

Weaning of lambs to eliminate the suppressive effect of lactation on resumption of reproductive cycles is common place in sheep farming. This allows a ewe’s BCS to be improved in preparation for the next breeding season.

Project Objectives:

The overall objective of the proposed project is to investigate the potential benefit of continuous suckling/“ewe rearing” on the productivity of sheep enterprises. The specific objectives include:

1. To determine the effect of continuous suckling/“ewe-rearing” with and without supplementation on growth rate of lambs.

2. To determine the effect of continuous suckling/“ewe-rearing” with and without supplementation on degree of parasitism of lambs.

 
3. To determine the effect of continuous suckling/“ewe-rearing” on weight and body condition changes of ewes.

4. To compare the economic benefit of continuous suckling/“ewe-rearing” of lambs to market to the traditional practice of weaning lambs and fattening to market.

Cooperators

Click linked name(s) to expand
  • Kellie D'Souza
  • Dr. Marlon Knights
  • Dr. Doolarie Singh-Knights
  • Brad Smith

Research

Materials and methods:

To achieve the objectives of the study, two trials involving 7 replicates were conducted with mature ewes and their fall or spring-born lambs. Trial 1 included 3 replicates. In replicate 1 ewes and lambs (fall-born) were fed second cutting orchard grass hay ad libitum. In replicates 2 and 3 and in Trial 2 the ewes and lambs (spring-born) were allowed to freely graze pastures

 

Trial 1:

Replicate 1: Late summer-born, crossbred Katahdin lambs (n = 68), with an average weight of 17.2±0.6 kg, were randomly assigned within birth-type, sex, and average age to be weaned (W) at approximately 77d or to continuously suckle (S) ewes until they attained market weight. Half of the lambs in each suckling status group were assigned to be supplemented (WS, n=16; SS, n=17) or not supplemented (WNS, n=18; SNS, n=17). Fall-born lambs and their dams were housed on dry lots, fed orchard grass hay and had free access to minerals and water for throughout the duration of the experiment. All lambs were vaccinated with two doses of CD-T at weaning and again 4 weeks later. Supplement was a 16% crude protein, 3.5 % crude fat, lamb pellet offered ad libitum to the supplemented groups. Lambs were weighed at birth, at the initiation of the trial, and at approximately biweekly intervals for three (3) months.

 

Replicates 2 and 3: Was designed similar to replicate 1, except the lambs (n =98, 41 for replicates 2 and 3) were born in spring, weighed, 20.4 ± 0.5, 19.3 ± 0.5 kg and were 82 or 79 days of age in replicates 2 and 3, respectively. All ewes and lambs (WS, n=24, 10; SS, n=28, 10; WNS, n=18, 11; SNS, n=17, 10) were turned out on pasture. To maintain a consistent grazing pressure among treatment groups, pastures with weaned lambs (W) and ewes with lambs (S) were stocked at a rate of 6 animals per acre. Another replicate, in which lambs were assigned to treatments, was discontinued after the producer continuously sold the largest lambs from the SS treatment group prior to end of the observation period.

 

Trial 2:

Replicates 4-7: Poor growth of weaned lambs that were not supplemented was observed in Trial 1. Therefore in Trial 2 all lambs were supplemented. Briefly, lambs were separated into 2 groups, suckling, supplemented (SS, n = 42) or weaned, supplemented (WS, n = 41). The average weight and age of lambs was 32.1 kg and 75 days, respectively, and was on trial for a mean of 50 days.

 

In replicates 2-7, fecal samples were collected at initiation of the trial and once a month thereafter from a subset of lambs from each treatment group. Fecal samples were processed using McMaster’s solution and fecal eggs were counted. After consulting with our Parasitologist, we focused on the Trichostrongylid family of which Haemonchus contortus is a member and one of the most important parasites to control in our area. Animals with Haemonchus contortus infections can suffer from anemia, emaciation, edema, intestinal disturbances resulting principally from loss of blood and injection of hemolytic proteins in the host's system. Heavy infections may be fatal.

 

To assess the effect of weaning on weight and body condition of dams, the dams of the weaned lambs and continuously suckled lambs (n =106, 109 respectively across all trials) were weighed at the start of each trial and their body condition score (BCS) determined by an experienced evaluator. Weights and BCS evaluations were taken at monthly intervals thereafter.

 

To assess the economic benefit of continuous suckling, a partial budget analysis was conducted. We assumed no difference in price or mortality due to system of management and no increases in cost as both CS and weaned lambs were given equal access to the grain supplement.

Research results and discussion:

  1. Effect of Continuous suckling and supplementation on growth performance

Trial 1: The mean initial weight of lambs was 19.5 ± 0.4 kg (Table 1). Total weight gain and ADG were significantly higher (~ 3.4 kg, 30g/d respectively, P < 0.001) in continuously suckled than in weaned lambs and in supplemented compared to lambs not supplemented (~ 8.8 kg, 77 g/d respectively, P< 0.001).

Trial 2: The mean initial weight of lambs was 32.1 ± 0.2 kg (Table 2). Total weight gain and ADG were significantly higher (~5.2kg, 89.7 g/d, respectively, P < 0.05) in continuously suckled than in weaned lambs when both groups were receiving supplementation.

  1. Effect of continuous suckling/“ewe-rearing” on degree of parasitism of lambs.

There was no effect of suckling on the parasite load of Trichostrongylid in lambs.

 

  1. Effect of continuous suckling/“ewe-rearing” on weight and body condition changes of ewes

Trial 1: The mean initial, final and weight changes in ewes were 48.2 ± 0.8, 52.6 ± 0.9 and 4.5 ± 0.4 kg, respectively, and was not affected by treatment. The mean BCS of ewes at the start of the experiment was 2.4 ± 0.02. BCS of ewes increased to 3.1 ± 0.02 at the end of the trial and was not affected by treatment.

Trial 2: Data on weight and body condition scores of ewes in Trial 2 is presented in Table 3. There was no effect of suckling on weight, BCS or on weight and BCS changes of ewes.

Research conclusions:

  1. Contribution to agricultural sustainability

    1. The findings of this study indicate that continuous suckling/ “ewe-rearing” results in higher growth rates and total weight gain at market, while potentially eliminating the stress associated with weaning and reducing mortality. These findings point to a management practice that improves animal welfare while simultaneously increasing productivity, profitability (~$25.00/lamb), and sustainability of sheep operations.

 

  1. Potential impact on farm practices

    1. The results of these studies indicate that “ewe-rearing” of lambs is a simple management practice that producers might employ to enhance the productivity and profitability of small-scale sheep operations in the Northeastern United States. The practice generally does not require any additional handling or incur any additional cost to implement but increases lamb output.

 

  1. Effect on secondary audiences

    1. “Ewe rearing” of lambs does not incur any additional cost while has the potential to increase farm income. It is expected that this practice will be adopted by producers who are made aware of the results of our studies. A bulletin will be written for the West Virginia Small Ruminant Producers (WVSRP) where both sheep producers and Agriculture Service Providers will have access to our findings. The final results will be presented to producers at the next Annual Short-course held by the WVSRP, which has had an average attendance of over fifty producers and eight extension agents. Additionally, we will plan to present our findings at educational programs hosted by county extension agents.
    2. There is also potential to present the final data at one of the Animal Science meetings in the coming year.

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

  1. Simpson-Rastle, S.L., and Knights, M. (2011). Overview of project “Effect of continuous suckling /”Ewe rearing” on growth and level of parasitism of lambs and on productivity and profitability of lamb operations. West Virginia Small Ruminant Project Panel Discussion, March, 2011, Davis College of Agriculture, West Virginia University, Morgantown, West Virginia..
  2. Simpson-Rastle, S.L., and Knights, M. (2012). “Effect of continuous suckling /”Ewe rearing” on and supplementation on growth performance of pasture-raised Katahdin Lambs. An Update. West Virginia Small Ruminant Project Annual Short Course, Spring, 2012, Franklin, West Virginia.
  3. Simpson-Rastle, S.L., D’Souza, K.N., Baptiste, Q.S. and Knights, M. (2012). Effect of continuous suckling/ewe-rearing and supplementation on growth performance of Katahdin lambs. Joint Annual Meeting of the ADSA/ASAS Phoenix, AZ, USA, July 15-19, 2012. J. Anim. Sci. 90: (Suppl. 3):385
  4. Simpson-Rastle, S.L, D’Souza, K.N., Redhead, A.K., Baptiste,Q.S. and Knights, M. (2013). Effect of continuous suckling/”ewe-rearing” and supplementation on growth performance of pasture-raised Katahdin lambs. Joint Annual Meeting of the ADSA/ASAS Indianapolis, IN, USA, July 8-12, 2013. J. Anim. Sci. 91: (Suppl. 2):606
  5. Simpson-Rastle, S.L, D’Souza, K.N., Redhead, A.K., Baptiste,Q.S. and Knights, M. (2013)Effect of continuous suckling/”ewe-rearing” and supplementation on growth performance of lambs and reproductive performance of ewes. Annual Sheep Short Course, November 2nd, 2013. West Virginia University Organic Farm, Morgantown, WV.
  6. We wrote a draft a paper with the results from Trial 1 but decided to wait and collect and include data from Trial 2 in the same manuscript. Final preparation of the manuscript including results from Trial 2 is ongoing.

Project Outcomes

Project outcomes:

Using an average price of $2.10 per pound for feeder lambs, pulled from the USDA Weekly National Lamb Market Summary from Friday September 12, 2014, we calculated a partial budget analysis. We wanted to determine any potential increase in revenue for our producers due to a change in weaning practice. We assumed no difference in price or mortality due to system of management and no increases in cost as both CS and weaned lambs were given equal access to the grain supplement.

 

Trial 1: Total additional profit for 50 head of lamb was $628 (~$13/lamb; Partial Budget 1). Due to the smaller breed of lambs used, there was not as much difference in end weights between weaned and suckling lambs as we realized in trial 2.

Trial 2: Total additional profit realized for 50 head of lamb was $1,266 (~ $25/ lamb; Partial Budget 2). Ewe-reared lambs in trial 2 grew at 90g/d faster than weaned lambs over the 50 day trial period. For a grow-out period of 100 days, there could have been additional income of approximately $829 for the 50 head.

Farmer Adoption

The response we have received from our producers has been positive. The farmers that we worked with on this project seemed receptive to using this practice in the future to take advantage of the higher prices per head due to the increased end weight. We are still talking to farmers about adopting this practice and will be presenting our complete results at this year’s Annual Short-Course.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

  1. Most of these trials were done with lambs born in the spring when they would normally be born. We need to do more work with lambs born in the fall, however at this time of year, the animals have to be placed in dry lots and have access to hay not pasture.
  2. While we were successful in demonstrating improvements in daily and total weight gain, we were not able to quantify differences in feed consumption and feed conversion efficiency. That is, were the improvements observed due to maintaining or increasing feed consumption, better feed conversion or due to a combination of both?
  3. There is need for continued research on the impact on morbidity and mortality

 

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.