Early lamb losses and reducing antibiotic use

Lamb mortality risk factors

Lamb losses can have a huge impact on welfare, production and farmer morale. It can be multifactorial but also highly variable depending on the individual farm and production system. Some of the major risk factors associated with losses are birthweight, colostrum intake (quantity and quality), dystocia, indoor versus outdoor lambing, hygiene, litter size, genetics, mis-mothering etc. Many factors can be interlinked, for instance, ewe nutrition and litter size, or low birthweight and colostrum intake. It is important to assess this every season as it may change depending on circumstances to target the areas that need improving.

Low Birthweight

Lamb mortalities are highly correlated with low lamb birthweights. The most common causes for this is poor ewe nutrition pre-lambing, litter size and ewe illness. Ewes giving birth to triplets and quads are more likely to produce smaller lambs which have less brown fat and are at a greater risk of not feeding, losing heat and becoming hypothermic. Poor ewe condition and nutrition in late pregnancy causes poor udder development, milk quality and quantity, milk let down with deprived feed intakes/ poor growth rates in lambs.

Prevention of low birthweight

• Regular body condition scoring to detect problems early. Ewes should be in a good BCS pre lambing/at lambing (lowland 3/5, hill/upland 2-2.5/5 BCS)
• Investigate problems (diet, parasitism, age, disease)
• Scan ewes to provide correct ration for scanning results, body condition and weight
• Metabolic profiling (blood sampling with vet) 4-6 weeks prior to lambing to monitor sufficient energy
• Perform a forage analysis and seek help to ration properly. Ensure good management of feeding to maintain and maximize intakes and trace elements.
• Minimise triplets

A 4kg lamb should have 200 mls of colostrum in the first 2 hours of life and 800 mls in the first 24 hours.

Little size

Litter size is mainly determined by body condition at tupping and genetics. Breeds, such as Lleyn, Blue Faced/mules and Dorsets, are known for large liter sizes. Multiples need extra colostrum and are more at risk of starvation and mis- mothering, through lack of attention, teats and colostrum quantity.

Prevention of large litter size

• Avoid flushing in prolific breeds as there is a direct correlation to high lamb mortalities. Flushing is a technique used to increase body weight fast to increase the ovulation rate to produce a higher lamb crop). Ewes that are flushed too thin are at a higher risk of multiples and subsequent metabolic deaths (eg. twin lamb disease)
• Focus on maintaining body condition throughout the year
• Be careful with prolific breeds

Genetics

Genetics play an important role influencing mortality in your flock. EBVs (Estimated Breeding Values) are values assigned to animals that predict the likely performance of offspring for various traits. They are calculated from the animals own performance and from the performance of its relatives recorded by pedigree breeders. 1 Ram EBV’s traits can be found in sales catalogues and can include:

• Lambing ease
• Mothering ability
• Lamb birthweight
• Lamb vitality (target time to stand and suck is 30 minutes)
• Milk yield (daughter traits- some linked to milk yield)
• Litter size (breed)

Active decision making can start with record keeping on lambing assistance, lamb mortality (reasons) and mothering ability. You can use your records for genetics management, culling and ram selection. EBV’s are a tool that offers an opportunity of using information in conjunction with your standard ram selection.

Low colostrum intake

Lambs are born with NO immunity. Colostrum is the first form of milk produced that contains antibodies (and other essential nutrients) to build up the neonate’s immune system.

Causes of low colostrum intake can be due to poor supply (amount, quality or let down) from the ewe. It can also be due to low lamb birthweights, hypothermia, mis- mothering, traumatic birthing and multiples. Colostrum supply from the ewe can be lower in volume per lamb, delayed let down and poorer quality when ewes are in low BCS and/or deficient in protein and energy in the last 4 weeks of pregnancy. Mis-mothering can delay or prevent colostrum intake due to high stocking density, disturbance during lambing, first time mothers, movements and hungry/thirsty/ill ewes. #COLOSTRUMISGOLD

Ensuring colostrum intake for immune support

• Ensure adequate ewe nutrition through body condition scoring and pre-lambing nutrition
• Check for suckling within 2 hours- supplement (if not suckled, triplets/quads, sick ewe or difficult lambing)
• Check for milk in abdomen- behind ribs for empty/hollow belly. If in doubt, supplement.
• Consider farm policy for triplets- tube/supplement ALL triplets. Look at economics of removing 3rd lamb to foster vs feeder. Will help growth rates, survival and minimise ewe weight loss lactation
• How to choose a colostrum type?
  • COLOSTRUM FROM DAM > Other ewes colostrum > Frozen > other species> Artificial powdered (LAST RESORT)
• How much? Weigh lamb
  • Give 50mls per kg in the first 2 hours (4kg lamb should have 200 mls in first feed)
  • Ensure 200mls per kg over the first 24 hours (4k lamb should have 800 mls in total within the first 24 hours)
• Comatose/hypothermic lambs (unable to lift head/ swallow with temperature of <37C)
  • Under 6 hours- heat first, then feed (tube vs bottle depending on suckle reflex)
  • Over 6 hours- Inject glucose (intraperitoneal), heat, then feed (tube vs bottle depending on suckle reflex)
• Quality of Colostrum
  • Check quality of colostrum through measuring antibody levels with a Brix refractometer
  • Brix of 22% or higher can be used. Levels less than 22% should not be used as a first line colostrum feed
• Frozen Colostrum storage tips
  • Take colostrum off of milky dam with single or a dam whose lamb died shortly after birth (not aborted/stillbirth)
  • Store in liquid tight container (bottle, bag) 150-250 mls, label with date, quantity
  • Frozen colostrum- DO NOT microwave. Warm slowly in a water bath to 38-39C
  • If not using then immediately fridge (4 C) for 2-7 days *care with fridge temp* or freeze (-20 C) for 6-12 months

Summary

The lambing season can already be tiring, but adding in lamb losses can be downright stressful and demoralising. There are many management changes you and your vet can make when you are suffering from a large amount of early lamb losses. The immediate focus may be colostrum intake, hygiene and vaccinations but there may also be a wider focus, for instance, ewe nutrition, practicing more body condition scoring and scanning your flock after tupping. These management tools will all indirectly reduce the amount of antibiotics you are using on farm. If you have any queries or would like to discuss your lambing losses, please phone the practice to speak to one of our vets.