Lecture 26- Sheep Nutrition

What type of grazers are sheep?

Selective grazers.

What production factor determines sheep feeding strategy?

Production phase.

What percentage of cost is feed in sheep production?

50-70%.

Which vitamins are synthesized in the rumen?

Vitamins A and K.

Which vitamin must be supplemented in sheep?

Vitamin E.

Which minerals are key for sheep?

Iodine, selenium, copper, cobalt.

What is the lowest-cost sheep production system?

Range/pasture with no buildings.

What is a major disadvantage of pasture-only lambing?

Higher lamb mortality and weather exposure.

Which system supports accelerated lambing?

Confinement-based systems.

Which breed is commonly used for accelerated lambing?

Dorset.

Which breed is the highest milk-producing sheep?

East Friesian.

What is a common terminal sire cross for meat sheep?

White-faced ewes × Suffolk/Hampshire/Dorset/Southdown/Shropshire.

What is the milk yield of dairy sheep?

0.75-2.0 lb/day.

What are the two dairy sheep systems?

Early weaning (3 days) and partial suckling (30 days).

What is the BCS scale for sheep?

1 (emaciated) to 5 (obese).

Where is BCS assessed on sheep?

Loin region (spinous and transverse processes).

What is the target BCS at breeding?

3-3.5.

What are the ewe nutritional phases?

Maintenance → Flushing/Breeding → Gestation → Lactation → Post-Weaning.

What is the DMI during maintenance?

~1.7% BW.

What is the CP requirement during maintenance?

~9.5%.

What is the goal of flushing?

Improve ovulation rate and fertility.

How much grain is used for flushing?

¼-½ lb grain/head/day.

What BCS should ewes have at flushing?

3-3.5.

When should flushing occur?

4 weeks before ram introduction.

Which ewes respond best to flushing?

Mature ewes early or late in breeding season.

What is the most critical nutritional period for ewes?

Late gestation.

What happens with poor late-gestation nutrition?

Lighter lambs, low energy reserves, uneven twin birth weights, pregnancy toxemia.

What is the DMI in late gestation?

~2.6% BW.

What is the CP requirement in late gestation?

10.5-11.5%.

What increases energy needs in late gestation?

25% increase for singles; 35% for twins; 45% for triplets.

What is the energy demand during lactation?

3× maintenance.

When is peak milk production in ewes?

2-3 weeks postpartum.

What is acceptable BCS loss during lactation?

Up to 1 BCS point.

What is the DMI during lactation?

3.5-4.5% BW.

What is the CP requirement during lactation?

13-15%.

What supplementation is needed during lactation?

Grain supplementation.

What are major energy-related nutritional problems in sheep?

Pregnancy toxemia and hypothermia in lambs.

What causes pregnancy toxemia?

Inadequate late-gestation nutrition, especially in ewes with multiples.

What metabolic process increases during pregnancy toxemia?

Gluconeogenesis and fat mobilization.

What clinical signs occur in pregnancy toxemia?

Decreased appetite, neurologic signs, recumbency → death.

What causes hypothermia in lambs?

High surface area, low fat reserves, inadequate colostrum.

How is hypothermia treated?

Warming and intraperitoneal glucose.

What percentage of lamb energy intake comes from fat?

~50%.

Why do housed lambs get iron deficiency?

Lack of soil exposure; require iron supplementation.

What is creep feed CP for lambs?

16-20% CP.

When does creep feed intake begin?

3-4 weeks.

Why is creep feed important?

Supports rumen development.

What causes copper toxicity in sheep?

Acute overdose or chronic accumulation from excessive dietary copper.

Why are sheep sensitive to copper?

Their liver stores copper efficiently.

What triggers copper release from the liver?

Stress (handling, shearing, transport, weather).

What are signs of copper toxicity?

Sudden death, elevated liver enzymes, hemolysis.

What causes urolithiasis in sheep?

High grain diets, low Ca:P, high Mg, low water intake, early castration.

How is urolithiasis prevented?

Ca:P ratio 2:1, good water access, urinary acidifiers.

What are the ADG and CP needs of growing lambs (45-80 lb)?

ADG 0.5-0.8 lb/day; CP 14-16%.

What are finishing lamb diet characteristics?

High-energy diets with risk of enterotoxemia and urolithiasis.

What causes enterotoxemia in lambs?

Clostridium perfringens type D proliferation on high-starch diets.

What are the key takeaways for sheep nutrition?

Late gestation & lactation are highest risk; BCS drives reproduction; flushing improves ovulation; sheep are copper-sensitive; nutrition impacts lamb survival.