Final Report for ONE13-174
Early weaning (EW) of lambs when they are 3 months or less followed by finishing in feedlots or on pasture is a common management practice among lamb producers. EW is thought to reduce the nutritional demand on the ewes which should allow for optimum performance in the subsequent breeding period. However, EW has been associated with compromised health, depressed growth, and increased mortality in lambs and may not be necessary as there is an increasing demand for younger lambs at lighter slaughter weights. Using 502 lambs located on seven farms in WV, PA and MD we were able to demonstrate that lambs that are continuously suckled (CS) grew faster and gained more total weight than lambs that were weaned at an average of 70 days of age. A partial budget analysis revealed that lambs that were CS earned $26.13 ($9-$67) more on average and generated a 16-24% increase in profit. Moreover, ewes that were reared continuously with their lambs showed similar reproductive outcomes to ewes from which lambs were weaned. Participating producers as well as those attending educational programs expressed a willingness to implement the CS management strategy. Therefore, 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.
The traditional and widely used practice of weaning lambs of their dams at 2-3 months of age is associated with depression in growth and increase morbidity of lambs which can have deleterious effects on the productivity and profitability of sheep operations. 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. Initial results from studies conducted by a NE SARE graduate student recipient showed an increase in weight gain/market weight of between 3-5 lbs in lambs continuously reared with their dams compared to lambs weaned at 2.5 months. The positive benefits of continuous suckling was observed in lambs regardless of whether they were given adlibitum access to concentrate feed or reared on pastures or given hay only (un-supplemented). We are encouraged to evaluate and extend this strategy to as wide a range of producers as possible as the adoption of this strategy could help to stem the decline in the number of small-scale sheep operations in Appalachia by increasing profitability of operations. If realized, increases in weight gain of lambs across the state of WV, would result in an additional 150,000 lbs of lamb produced annually, equivalent to an additional $300,000 in revenue. Interestingly, this finding suggest that high levels of growth rate can be achieved in pasture raised lambs without the need for supplementation, resulting in significant savings on feed cost. An increase demand and price for lighter (< 100 lbs) market lambs in the Northeastern United States (Singh et al., 2005), provides an additional incentive for adoption of this strategy, as lambs for this market can be finished on pasture while still suckling their dams.
- Knights, M., Siew, N., Ramgattie, R., Singh-Knights, D and Bourne, G. (2012). Effect of Time of Weaning on Reproductive Performance of Ewes and Growth of Lambs in Barbados Blackbelly Sheep reared Under a Tropical Photoperiod Small Ruminant Research 103:205-210.
- Singh-Knights, Doolarie, D. Smith and M. Knights (2005). “Developing Needed Price Premiums for Selecting Optimal Marketing Strategies for Sheep Producers in West Virginia.” Agricultural and Resource Economics Review. Vol. 34 (2): 286.
Specific objective 1: to determine the effects of continuous suckling and supplementation on growth rate of lambs.
Specific objective 2: to determine the effects of continuous suckling and supplementation on level of parasitism.
Specific objective 3: to determine the effects of continuous suckling on weight changes and body condition of ewes.
Specific objective 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.
Specific objective 5: Increase awareness of the benefits of continuous suckling.
A total of 442 lambs from 7 flocks were used in this study. Breed of sheep was confounded with flock and included graded Katadhin (Flocks WD1, WD2 and WD3), Texel X Dorset cross (Flock GW), Purebred Dorset (Flock MT) and Cross bred Suffolk (Flocks EM and JD). The mean weight of lambs at the start of the study was 24.6 ± 1.0 kg and varied with flock. Initial weights varied from 17-34 kg and was lowest in flock with Katadhin sheep (Table 1). In initial replicates half of the lambs in each weaning type group was given ad libitum access to a 14-15% crude protein supplement or to pasture or grass-legume hay only. Due to the poorer performance of un-supplemented lambs (forage only diet) in subsequent replicates lambs assigned to both weaning types were supplemented. Lambs were born to either spring or fall lambing and randomly assigned within type of birth and sex to be weaned or remain continuously suckling their dams. Groups were then balanced for age. As lambs were born in different months throughout spring and fall, measurements were collected from October through August in the different flocks.
To determine the effects of continuous suckling and supplementation on growth rate, lambs were weighed at the start of the experiment and at bi- weekly or monthly intervals. Weights were determined on un-fasted lambs using a digital sheep scale (model VS-660; A & A sales, LLC, NJ). Lambs in a given flock were all weighed on the same day and measurements were completed within 2 hours. The average daily gain (ADG), total weight gains (TWG), and final weight for lambs in each treatment group were calculated.
To determine the effects of continuous suckling and supplementation on level of parasitism, fecal and blood samples were collected on 40 CS and 40 weaned lambs from 4 flocks at the start of the experiment and monthly intervals thereafter, for determination of fecal egg count (FEC) and packed-cell volume (PCV). Due to difficulties encountered in conducting the PCV analysis on farm only FEC was assessed.
To determine the effects of continuous suckling on weight changes and body condition of dams, the weight and BCS of ewes from lambs assigned to both treatment groups in a subset of replicates were weighed at the start of the experiment and at monthly intervals.
To compare the economic benefit of continuous suckling/“ewe-rearing” of lambs to weaning lambs prior to growing and fattening to market, a partial-budget analysis was conducted and used to determine the production system with the highest net return.
To increase awareness of the benefits of continuous suckling we collected and discussed results in collaboration with participating producers and presented findings at educational meetings conducted in WV and PA at which over 60 producers attended. A scientific manuscript was prepared and an article for publication on the WVSRP page and newsletter was written.
- Effect of Continuous suckling and supplementation on growth performance.
The mean growth rate and total weight gain was 162 and 81.2 g/d and, 12.5 and 6.8 kg for lambs CS and weaned lambs respectively. Lambs that were CS grew faster and gained more weight on all farms. The difference in growth rate and weight gain ranged from 19-210 g/d and 1.9 and 14.5 kg, respectively (Figures 1 and 2).
- Effect of continuous suckling/“ewe-rearing” on degree of parasitism of lambs.
Fecal egg counts was measured on 40 weaning and 40 suckling lambs across 4 flocks. The mean fecal egg count of Trichostrongylid worms in lambs was 1317 ± 172 and was not affected by weaning (1454 ± 253 and 1505 ± 263 for CS and weaned lambs respectively). The mean egg count increased progressively throughout the growing period and was higher after the second month on pasture (2328 ± 383) than at beginning of the trial (1183 ± 276; P = 0.0163) and the after the first month on pasture (927 ± 277; P = 0.0035).
- Effect of continuous suckling/“ewe-rearing” on weight and body condition changes of ewes.
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.
- Reproductive Performance of Ewes CS lambs and Dry/ (non-suckling) Ewes.
Means for reproductive performance variables of postpartum ewes that were weaned or continuously suckling their lambs are presented in Tables 1 and 2. Fall lambing ewes that are re-bred towards the end of the natural breeding season had higher pregnancy rates and prolificacy than ewes lambing in spring (75 vs 54% and 2 vs 2.4 for CS and Dry ewes, respectively; Table 1). This difference in reproductive performance is consistent with a high proportion of fall lambing ewes returning to cyclicity postpartum during the latter part of the annual breeding season (December-January). In contrast the postpartum period of spring lambing ewes coincides with the seasonal anestrous period which reduces the ability for these ewes to rebreed. This is consistent with the findings of Lewis and Bolt (1983), who reported that ewes giving birth during the stimulatory photoperiod of the fall returned to cyclicity by 32 days postpartum.
The pregnancy rate, percent of ewes lambing and the prolificacy did not difference between CS and dry ewes (Table 2). There was a trend towards a suckling status X lambing season interaction, with the impact of CS tending to be more deleterious to reproductive performance in spring compared to fall-lambing ewes. The generally held view that weaning is necessary to enhance subsequent reproductive performance was not observed in this study, in particular in fall-lambing ewes. Similar conception rates in early postpartum (day 50) dry and lactating ewes was previously reported by Warren et al. (1989).
- The economic analysis was done using a partial budget analysis =
- Additional revenue + reduced cost – decreased revenue + increased cost)
The assumptions used in calculating the partial budget analysis included the following:
- The typical market lamb weighs 45.5 kgs
- Average price of $4.62/kg for feeder lambs, (USDA Weekly National Lamb Market Summary from Friday September 12, 2014)
- There were no cost difference between groups. We assumed both groups consumed the same amount of feed and required the same amount of other inputs.
- There was no decrease in revenue (mortality rate was assumed to be the same)
- Weight gain range for weaned lambs = -3.5 – 14 kgs with a mean of 6.8 kgs
- Weight gain range for CS lambs = 4 – 19.6 kgs with a mean of 12.54 kgs
The revenue generated from weight gain was $31.37 with a range of $-16.10 to $64.40 per weaned lamb and $57.68 with a range $18.4 to $90.16 per CS lamb. The average difference in value of weight gained between CS and weaned lambs was $26.13 per lamb.
- Lewis, G.S., Bolt, D.J., 1983. Effect of suckling on postpartum changes in 13,14- dihydro-15-keto- PGF2 alpha and progesterone and induced release of gonadotropins in autumn-lambing ewes. J. Anim. Sci. 57, 673–682.
- Warren, J.E. Jr., Kiesling, D.O., Akinbami, M.A., Price, E.A., and Meredith, S., 1989. Conception rates in early postpartum ewes bred naturally or by intrauterine insemination. Anim. Sci. 67, 2056-2059.
a. Continuous suckling increased the total weight gain in lambs by 4-32 lbs across breeds and farms. The better growth rate and weight gain observed in continuously suckling lambs was evident in lambs receiving or not receiving supplementation. Producers benefitted from higher total pounds of lambs marketed in the continuously suckled lambs. These lambs earned on average and additional $25.00 each. These findings point to a management practice that improves animal welfare by eliminating the stress associated with weaning and reducing mortality while simultaneously increasing productivity, profitability (~$25.00/lamb) and sustainability of sheep operations
b. Continuous suckling of lambs does not affect subsequent fertility of ewes lambing in the fall, and only negligible effects were observed in spring lambing ewes. This indicates that ewes can be rebred successfully without the need for early weaning resulting in improved growth of lambs and increased frequency of lambing.
c. During the period 2012-2014, approximately 80 producers attending our annual sheep short course or attending other educational meetings were made aware of the benefits of continuous suckling. “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 is being be written for the West Virginia Small Ruminant Producers (WVSRP) which would allow all 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.
Education & Outreach Activities and Participation Summary
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. D’Souza, K.N., Singh-Knights, D. and Knights, M. (2013). A Risk Management Strategy for Sheep Producers: The Benefits of Breeding Sheep Outside their Normal Breeding Season”. 2013 Extension Risk Management Education National Conference. Denver, CO, April 3-4, 2013
7. Knights, M. (2014). Efficiency of Small Ruminant Reproductive Management. Invited Presentation. Joint Annual Meeting of the ADSA/ASAS Kansas City, MO, USA, July 20-24, 2014. J. Anim. Sci. 92: (Suppl. 2):738. (included data from weaning studies indicating weaning was not necessary for high fertility).
8. Knights, M. (2014). Concepts for Increasing Productivity and Profitability of Meat Goat Operations. Invited Presentation. West Virginia University Small Farms Conference, Morgantown, WV, USA, February, 27, 2014. (included data from weaning studies indicating weaning was not necessary for high fertility in sheep)
9. D’Souza, K., Singh-Knights, D., Simpson, S. and Knights, M. (2014). Characteristics of Female Small Ruminant Producers in WV-Implications for Extension Training and Industry Support. 2014 Women in Agriculture Educators National Conference, Indianapolis, IN, USA, April 3-4, 2014. http://www.agrisk.umn.edu/Library/ConferenceMaterials.aspx?ConfID=13
10. Knights, M. (2015). Increasing productivity and Profitability of the Ewe Flock. Educational Meeting Lewis County, WV. March 17th. 2015. Bruce Loyd Extension Agent
11. Knights, M. (2015). Increasing productivity and Profitability of the Ewe Flock. Educational Meeting Beaver County, PA, April 18th, 2015. Walter Bumgarner, Extension Agent
Preparation of the manuscript is ongoing
The revenue generated from weight was $31.37 with a range of $-16.10 to $64.40 per weaned lamb and $57.68 with a range $18.4 to $90.16 per CS lamb. The average difference in value of weight gained between CS and weaned lambs was $26.13 per lamb.
If this is projected on to a typical flock in Appalachia that markets 50 lambs per breeding, CS will result in additional profit of approximately $1306.50
All participating producers acknowledged the benefits of delaying weaning and are likely to adopt this management strategy once it is consistent with other management strategies. Adoption of continuous suckling management strategy have been aided by the demand for lighter lambs and fast pre-weaning growth rates observed in creep fed/supplemented suckling lambs. These factors allow producers to market lambs at younger ages when lambs are often still managed with their dams. Participating producers also agree that it is economically beneficial to supplement lambs pre-weaning to take advantage of rapid early growth rates and high feed conversion efficiency and have largely adopted this practice.
Areas needing additional study
1. While we were successful in demonstrating improvements in average daily gain 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?
2. There is need for continued research on the impact on morbidity and mortality