Establishing and Grazing Native Warm Season Grass: How Average Daily Gain and Internal Parasite Burden are Affected in Weaned Lambs

View the project final report

Commodities

• Agronomic: grass (misc. perennial)
• Animals: sheep

Practices

• Animal Production: animal protection and health, feed/forage, grazing management, parasite control
• Crop Production: cropping systems

As stated before, the problem of weaned lambs on pasture in the South is being severely infected with barber pole worms and affecting economic profitability.  This is through death loss of lambs, reduced weight gain, and getting to market later than planned.  Going to market later may affect economics of an operation due to less lambs going to market during prime market days such as ethnic holidays where prices tend to be higher per pound.

My proposed solution was to establish an approximate 1.2 acre Native Warm Season Grass (NWSG) pasture for weaned lambs.  The NWSG pasture consists of mostly Big Bluestem, Little Bluestem, and Indiangrass, and was planted on May 1st, 2021 using a No-Till Truax seed drill.  These native plants are more sustainable because they require minimal, if any, fertilization and are prolific growers once established.  They are also more drought tolerant, which is more common during hot summers in the South, because of deeper root systems.  Each species has different maturity rates and can help to establish vigorous growth during the entire warm season growing period.  NWSG’s grow more erect and the average growth point is around six inches above the soil surface.  The proposed research is that the taller growing grasses will allow the weaned lambs to graze at head height or slightly higher heights and avoid grazing so close to the ground where the Barber Pole Worm is more commonly found.  NWSG establishment is more common in cattle operations, but the proposed research is to investigate the effectiveness of their use in small ruminant operations, specifically with sheep.  The other proposed benefit of establishing NWSG pastures for weaned lambs is better weight gains both from reduced internal parasite burden and from grazing nutritious warm season grass versus cool season perennial forage Tall Fescue KY-31 variety.  It has been well documented that KY-31 variety Tall Fescue creates performance issues in livestock in climates such as the Southeast, due to the fungal endophyte located within the plant.  While the fungal endophyte gives the plant improved drought tolerance and survivability it also can cause poor livestock performance when it is consumed in large amounts by livestock.  Common symptoms in livestock are delayed hair shedding and heat stress, along with reduced weight gain while grazing this KY-31 variety during hotter summer months.  Giving the weaned lambs a grass that doesn’t cause these performance symptoms could lead to higher overall weight gains and growing marketable lambs  (60-75 lb. live weight) sooner.  This would be particularly helpful in hitting the target market dates around ethnic holidays such as Ramadan, commonly beginning and ending in the months of May and June.  The other economic benefit would be reduced lamb deaths due to reduced internal parasite burden.

The NWSG pastures were mowed in late January 2022 but were not burned with prescribed fire.  Contemporary Groups of lambs were placed in their selected pastures on May 15th, 2022 and grazed for approximately 8 weeks.  30 lambs participated in the grazing study.  Weights and Fecal Egg Count (FEC) were taken every two weeks during the grazing period.  Lambs were dewormed based on FAMACHA minimum score of 3 before treated.

Final conclusion of the grazing trial was no difference in FEC between lambs grazing cool season and NWSG grasses (FEC removed on lambs dewormed).  There were no statistical difference in weights between lambs grazing cool season and NWSG grasses.  The one trend in the study was there was a greater proportion of lambs grazing cool season grasses required deworming compared to those grazing NWSG grasses.  Both sires of the contemporary groups were from National Sheep Improvement Program (NSIP) flocks that have Estimated Breeding Values (EBVs).  Estimated breeding values for FEC were used to analyze results where relevant.  The more negative the FEC EBV the more the animal is resistant to internal parasite burden.  Once the FEC EBV's were analyzed in those lambs dewormed, there was a trend of greater lamb FEC EBV associated with greater deworming.

To test this hypothesis, it took two years to get final results.  The first year, 2021, was used to establish and maintain a Native Warm Season Grass (NWSG) mix pasture of roughly 1.2 acres in size.  Any cool season perennials and other weeds were eliminated from the existing pasture using Glyphosate treatment after grazing a cover crop of Oats and Crimson Clover.  One Glyphosate burn down was done April 2nd, 2021. Then a follow-up burn down of Glyphosate, along with pre-emergent Panoramic, was performed the day of planting on May 1st, 2021.  The NWSG mix was established via no-till methods and with help from Jason Smith, NC Wildlife Resource Commission Biologist.  Jason brings a wealth of NWSG knowledge and experience with many years helping producers establishing successful NWSG plantings in North Carolina.  He calibrated the seed drill according to NWSG seeding recommendations for the planting.  Jason has assisted with monitoring initial establishment growth and giving recommendations on any post planting treatment of weed pressure.  He recommended mowing in January 2022 and Prescribed Burn if possible in year two.  In Jason's experience the first year should be used for establishing a good root system and monitoring plant competition and its effects on survivability.  

In year two, 2022, a contemporary group of lambs were separated at weaning time.  One group was put on the established NWSG pasture and rotationally grazed with electric netting and temporary water tanks.  Another group was divided and rotationally grazed on our base cool season perennial KY-31 Tall Fescue with a mix of warm season annual forbs and weeds/grasses.  Electric netting was used and temporary water tanks.  Breeding groups of lambs were sired by at least two different Rams.  Contemporary groups were comprised of lambs from both sires to avoid bias and more inconclusive results due to poor on-farm testing setup. 

Lambs from both groups were weaned the same day, weighed on our W100 Gallagher weight scale for performance records, FEC sample taken, and then dewormed with Prohibit sheep drench before exiting the sheep working system.  All lambs were kept together as one group for 7 days and fed 1% body weight a 16% lamb grower feed, with coccidistat, to start everyone on an equal playing field.  The lamb grower feed were given 3 times in the 7 day equalization period.

After seven days, each contemporary group were weighed again and divided and placed in their respective NWSG or Cool Season Perennial pasture.  Each group were fed the same sheep mineral and have full access to cool, clean water from our pressurized watering system.  Actual weights were conducted every 2 weeks during the testing period, mainly on Saturdays or Sundays, due to our full-time job responsibilities.  During the grazing trial FEC samples were collected at two week intervals for both groups to see if there is any statistical difference between the two groups.  This resulted in six FEC samples during the testing period to hopefully show further proof of reduced parasite burden while grazing NWSG pastures in the immediate post-weaning period of lambs.  Lastly, forage will be tested for protein levels and TDN levels before lambs enter the pastures to get a representative comparison.