Market Lamb Nutrition


Factsheet - ISSN 1198-712X   -   Copyright Queen's Printer for Ontario
Agdex#: 434
Publication Date: 02/03
Order#: 03-015
Last Reviewed: 11 February 2010
History: Original factsheet
Written by: Christoph Wand - Beef Cattle, Sheep and Goat Nutritionist/OMAFRA

 

Table of Contents

  1. Introduction
  2. Nutrients
  3. Feed Conversion Targets for Lambs
  4. Grain Feeding Strategies for Lambs
  5. Processing Grains
  6. Conclusion

Introduction

The purpose of market lamb feeding is to produce a product (quality and quantity) that is desired by the marketplace, and is conducted in a cost-effective manner. This objective must be kept clearly in mind at all times to ensure that proper business and animal management decisions are made.

The rumen, the largest of the 4 stomach compartments in ruminant animals, is a fermentation organ, not an acidic stomach. This means digestion is based on the microbes that inhabit the rumen and not on the abilities of the animal itself. Thus careful consideration must be given to ensuring the health of this environment.

Nutrients

There are several nutrients and nutrient classes that need to be addressed for optimum performance of sheep and lambs. They are listed in order of limiting hierarchy, that is, a factor lower in the list typically cannot supersede the importance of those higher on the list.

1. Water - Water intake is usually overlooked. The majority of gain is in fact water. Proper hydration also improves growth. As a result, the availability of clean water at all times is crucial for lambs. Waterborne minerals may interact with dietary compounds that may improve or inhibit the uptake of some nutrients.

2. Carbohydrate (CHO) - In a typical ration, energy is usually the limiting factor. In modern farm rations, carbohydrate is the prime energy source. There are 2 major categories:

  • Non-structural carbohydrate (NSC) - This includes starches and sugars. In a grain ration, starch is the primary source of NSC. NSC is the fraction of the feed that is likely to be associated with acidosis.
  • Structural carbohydrate (SC) - fibre and cell walls. These are found in the hull of grains and in forages. SC is less digestible and lower in energy that NSC, but SC is usually less expensive. Forage maturity is the major determinant of the digestibility of this fraction.

3. Protein - Typically, "protein" and "crude protein" (CP) are used interchangeably in livestock nutrition. CP is an estimate of the protein in a feedstuff based on the assumption that most proteins have a similar nitrogen content, where CP = percent (%) nitrogen x 6.25 for most feedstuffs. In mature animals with fully functioning rumens, lower quality protein or non-protein nitrogen (NPN) can be converted to high quality bacterial protein. In young lambs under 60 lbs. liveweight, the rumen may not be fully developed. As a result, protein quality is important. Young animals are more dependent on the presence of higher quality protein in the ration.

4. Vitamins, Minerals & Additives - Numerous vitamins and minerals must be included in the diets, and are usually included in commercial mineral/vitamin packages. Ensuring 50 to 75 IU or more of Vitamin E per day, and making sure the recommended levels of mineral are fed will help ensure improved meat quality. Coccidiostats are recommended. Please note that ionophore coccidiostats can improve feed conversion if delivered in an appropriate range. Consult your flock veterinarian and mineral supplier to ensure your needs are met.

5. Fats - an alternate form of energy, these are usually not of great importance in lamb feeding due to cost.

Feed Conversion Targets for Lambs

Feed Conversion Targets (Ratio Of Feed To Live Weight Gain)

  • Grass fed lambs introduced to a grain diet: 8.5-6.0:1
  • Grain fed from post-weaning (approximately 50 days of age) to market weight:
    • lambs to 36 kg (80 lbs.) liveweight - 4.0-3.0:1
    • lambs over 38-55 kg (85-120 lb.)
      liveweight - 7.0-5.0:1

Days To Market (DTM) And Average Daily Gains (ADG) Targets

Grass System

  • assuming May/June lambing
  • 150-250 days to market (DTM) at 43-48 kg (95-105 lb.) liveweight
  • low rate of gain [50-250 g (1/8-½ lb.) per head per day]
  • often under-finished without grain feeding

Grass and Finishing

  • required if grass lamb under-finished
  • poor utilisation of grain relative to grain based system
  • same as grass system plus 3-6 weeks grain feeding (refer to "Grass System")

Grain Based Confinement System

  • grain only diet from weaning to market weight
  • 100-140 DTM at 43-48 kg (95-105 lb.) liveweight
  • gain -325 g (3/4 lb.) per head per day
  • 4.0:1 feed conversion
  • risk of over-finishing if corn is the primary grain

Grain and Hay

  • 110-180 DTM
  • gain - 250 g (½ lb.) per head per day
  • 6.0:1 feed conversion

 

Grain Feeding Strategies for Lambs

Transition Diets

As with all ruminant livestock, lambs require transition diets when introducing a new ration in order to ensure rumen health. The transition period allows the microbe population to adapt to the new feedstuffs.

Grain Based Feeding System

Assuming a scenario where lambs have been creep-fed, and are weaned without having consumed appreciable amounts of forage (weaned at approximately 50 days and 18-27 kg (40-60 lb.) liveweight), the following recommendations can apply:

  • continue feeding creep diet for 2 weeks after weaning, that is, the creep and "receiving" or "starter" ration are the same (17% CP, 85% TDN, plus molasses)
  • a growing/finishing ration for lambs over 27 kg (60 lb.) (15%-16% CP, 80%-85% TDN)
  • a separate ration for animals over 40-45 kg (90-100 lb.) (13%-14% CP, 75%-85% TDN)

As animals make the transition from one level to another, allow 3-7 days over which the new diet is blended into the previous one at increasing rates. For example, 25% new diet and 75% old diet for 2 days, then 50:50 proportions for 2 days; followed by 75% new diet, 25% old diet for 2 days; and then 100% new diet.

Grass (Forage) Based System

The typical scenario would be grass lambs that require some additional finish. The assumption is that they are coming off an all grass or forage program.

  • Have a "Receiving Diet" that is at least 90% forage (less than ½ lb. grain per head per day). Preferably the forage is the same as previously fed, or similar.
  • Feed the receiving diet for 1 week.
  • Assuming the desired finishing diet is 80% or more concentrate, allow at least three weeks (21 days) and preferably 4 weeks to switch the lambs from the "Receiving Diet" to the desired diet. This is done in gradual and equal increases in concentrate.

Free-Choice vs Restricted Feeding

Regardless of what equipment is used, there are typically 2 strategies for feeding grain. One is free-choice feeding (also known as ad libitum, "ad lib", or full feeding) and another is restricted feeding (or limit feeding). Each has benefits and drawbacks and the producer must decide which strategy is most appropriate for his or her equipment and management ability.

Free-Choice Feeding

Free-choice feeding is often practised using a hopper type feeder, which has a continuous supply of feed where the hopper is not empty at any time. This provides a situation with constant storage and frees producers from making or delivering feed on a frequent basis. However, the drawbacks are that there is a risk that lambs will sort diet constituents, and there is no control over intake patterns. This makes lambs on free-choice feeding programs more susceptible to overeating, irregular intake and acidosis. For this system, allow 10 cm (4 in.) of feeder space per lamb, and ensure feeders do not go empty.

Restricted Feeding

This strategy is also known as limit feeding. By using the timing of feeding and manipulating the amount of feed delivered per feeding to control residual feed, this strategy is a powerful animal management tool. It allows more control over intake, more equal consumption of various diet components (e.g., grains Vs pellets) and allows for frequent assessment of feed intake and feed conversions. Its major drawbacks are increased labour requirement to deliver feed at least twice per day, and the increased need for additional bunk space to allow all animals to eat at one time. Restricted feeding at 90%-95% of the ad lib intake allows for improved feed efficiency, and is a strategy that is gaining popularity in the beef feedlot industry. This is known as "slick bunk management", "23 hour feeding" and "target feeding". To avoid trampling at feeding, allow 12-25 cm (5-10 in.) of feeder space per lamb, and observe animals diligently at feeding.


Textured Diets Vs Pelleted Diets

Once the commitment is made to feed grain, a ration type must be chosen. Each of the options has advantages and disadvantages in terms of the feeds that can be utilized, equipment requirements, cost and convenience features.

Textured Diets

  • allow the use of commodities (whole shelled corn, soybean meal (SBM), etc.)
  • molasses may be used in dry rations
  • to stimulate intake
  • to prevent sorting, binding minerals and medications to feed
  • causes serious handling issues
  • may be purchased or home-made
  • total mixed rations using silages and commodities are possible

Pelleted Supplement + Grain

  • small grains and corn comprise from 70%-90% of the total grain diet.
  • pelleted supplement comprises 30%-10% of the total grain diet
    • all vitamins, minerals and additives properly included
    • NRC reports intake may be lower on pellets
  • sorting of ingredients may occur
  • dependence on purchased materials and therefore feed cost implications

Processing Grains

"Processing" means milling or rolling grain. It is also referred to as cracking, grinding, hammer-milling and so on. Pelleted diets are grains that have been processed prior to pelleting and are considered processed. Generally, it can be assumed that processing adds about $10 per tonne to the diet cost, due to labour, power use and machinery upkeep.

Sheep are ruminant animals. They can utilize forages, fermenting them in the largest of four stomach compartments known as the rumen. The rumen is NOT an acidic stomach as is ours; it uses bacterial fermentation and requires a neutral pH, or a balance between acidity and alkalinity. Sheep excrete a buffer (bicarbonate) from the salivary glands while chewing. Thus, cud-chewing (rumination) promotes saliva production and rumen health. Coarser grains are better in most cases, as this promotes rumination and extends the amount of starch that is available for digestion over a longer period. This helps prevent acidosis - a condition to be avoided - where the rumen becomes acidic. In sheep, whole grains are sufficiently large to be ruminated and chewed, so they do not require processing, except in young lambs (creep feed). Processing grains stimulates intake, as the smaller particle size is more palatable to lambs. General processing rules of thumb are:

  • for lambs less than 9 kg (20 lb.) liveweight, process all grains
  • for lambs less than 22 to 27 kg (50-60 lb.), corn should be processed
  • once lambs exceed 27 kg (60 lb.), all grains can be fed whole without compromising intake, while reaping the benefits of whole grain

Avoid processing unless required. In most cases, this means processing only young lamb rations. In some cases all pelleted diets may be of sufficient benefit on account of their handling attributes that their biological drawbacks are overshadowed. Feeding whole grains improves rumen health in lambs as compared to feeding processed feeds, which includes grains that are ground and then pelleted. Improved rumen health means improved performance.

Conclusion

In certain situations, specialized feeding programs for market lambs are ideal. These include situations where extra value can be gained by investing in the additional feed and labour. The producer must moderate his or her expectations, depending on the flock production system. Various aspects of diet preparation must be considered to optimize nutrients delivered, and to ensure lamb health. Producers are encouraged to implement market feeding programs in consultation with nutrition providers and veterinarians to ensure all aspects and information are taken into account.

 


For more information:
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E-mail: ag.info.omafra@ontario.ca