Seasonal Notes

 

• Autumn Management tips for Coopworth Sheep Producers
• Ovulation and the Breeding Ewe
• Ram Selection

 

Autumn management tips for coopworth sheep producers

Contributed by John Keiller, Coopworth Sheep Society Council Member

 

Livestock

Draft adult ewes into condition score groups pre joining to increase weight gain of lighter groups and hold heavy ewes at maintenance.

The aim is to get all females at condition score 3 plus pre lambing so that all have the opportunity to rear good twins.

This can also be done to ewe lambs if they are to be joined. Draft 3 ways with:

• > 42 kg targeted for slow growth
• 34 – 41 on fast growth to attain puberty
• < 33 at slow growth to be taken through dry until 1.5 yo

FEC monitor adult ewes to determine if requiring a second summer drench, monitor ewe lambs 6 weekly, check rams are sound and remove lame ones immediately, post joining drench and put on good feed to replace lost body reserves.

Pastures

Aim to remove dry residues and assist in the germination of clover at the autumn break. Post joining ewes can move into a simple 4 paddock rotation of one week on and 3 weeks off. This has proven to be a simple but effective tool at increasing pasture growth. It also allows a feed wedge to be developed, which allows higher stocking rates to be maintained over winter.

Ovulation & the breeding ewe

Contributed by Dick Wigan, DUNKELD COOPWORTHS.

 

Ovulation rate in the breeding ewe is influenced by the following factors:

• Nutrition as a lamb
  
• Nutrition between weaning and mating for a maiden ewe.
  
• Liveweight & condition score six months prior to mating
  
• Liveweight & condition score at mating
• Month of the year/breeding season
  
• Age of the ewe
  
• Breed strain/genetics of the ewe
  
• Hormones (artificially)
  
• Breeding supplements/flushing
  
• Teasing ewes

There are other factors that have some influence, such as water quality, shelter, maximum daylight temperature, rough handling by over enthusiastic dogs and their bad-tempered owners.

1. Nutrition as a Lamb
   The lifetime number of follicles on the ovary of the ewe lamb are established 50 days prior to birth. Therefore, the nutrition of the mother six weeks before and after birth is crucial in determining the lifetime productivity of the ewe lamb.
2. Nutrition between Weaning & Mating
   The aim should be to achieve 60 kgs. at 12 months of age. Ewes only weighing 40 kgs. at 12 months have their lifetime production restricted, even if they are fed well for the rest of their breeding life.
3. Liveweight & Condition Score six months prior to Mating
   Follicles begin their growth six months before they are ready to ovulate, so nutritional stress at this time leads to fewer ovulations. The main problem is that the ewes are at their maximum milk production at this time, and feed stress will detract from the success of the next lambing. There are approximately 2% fewer twin ovulations for each kilogram reduction in bodyweight at this time.
4. Liveweight & Condition Score at Mating
   A minimum of 60 kg is recommended, although higher weights are desirable. From an efficiency point of view, there is a limit to the maximum weights, because it means a lower than optimum stocking rate. Setting a maximum weight is difficult, and some New Zealanders are starting to select for the percentage ovulation rate per kilogram of ewe bodyweight. e.g. 3% ovulation per kilogram of weight, means a 50 kg. ewe with a 150% ovulation rate is desired. At 2% per kilogram, it is inefficient. Medium sized ewes from high fertility backgrounds are the most desirable.
5. Month of the Year/Breeding Season
   All ewes in all breeds of sheep are at their most fertile in April. The “so called” British breeds have a very well defined peak that commences in about the first week of February, increasing gradually to mid-April, when the fertility gradually decreases until mid-September. Merinos, Dorsets, Finns and East Friesians are receptive all the year round – all the “pink noses”!
   People who lamb any ewe, of any breed, from April to July can hardly be serious about reproductive rates, or fitting their feed requirements to the pasture production curve – the pastoral zones being the exception.
   Those who mate Coopworth cross and B.L./Merino ewes for a May lambing, usually achieve about 40% fewer lambs born, than those aiming for an August – September lambing.
6. Age of the Ewe
   Ewes of all breeds reach their peak of their mating at 4.5 years. Their decline is governed by their ageing process. Some sound ewes are still producing well as 9 year olds. Most decline quicker because of teeth wear and other ageing processes.
7. Breed/Strain/Genetics of the Ewe
   East Friesians and Finns are two breeds that were introduced to compete with Coopworth and Border Leicesters as “Maternal Crossing Breeds”. They are very fertile sheep, and it is their major selling point.
   Merinos are not very fertile, and it follows that the good reproductive rates of Maternal sires will be brought back to the field by Merino dams.
   There is little or no attempt by the Merino stud industry to do anything about poor fertility. The major problem is lamb survival, and the failure of the ewes to mother and rear their lambs. It is very easy to select for, and to make progress.
   Coopworths were originally bred from stud Romneys – 30% of which needed lambing assistance, and a 90% lamb rearing rate. There have been cases of mature Coopworth ewes rearing in excess of 180% lambs.
   It is essential to buy rams with good fertility backgrounds.
8. Hormones/Artificial
   These seem to have fallen out of favour in recent years, but it is still possible to increase the number of lambs born by injecting the ewes with drugs. e.g. P.M.S. (Pregnant Mare Serum)
9. Feeding Supplements/Flushing
   Bodyweight at mating is one of the most important factors contributing to high reproductive performance. Flushing – or added feed, is very important for lower bodyweight ewes. Lupins contain a particular protein that increases fertility.
10. Teasing
    This can help concentrate lambing if you wish to mate before the 1st of March. With maidens, it helps more of them to lamb in the first 17 day cycle. Tesgro injected wethers will do this for you.
    .

Ram selection

Contributed by Don Pegler, OAKLEA Coopworths

 

The first thing that anybody should consider when selecting a ram is what they want the ram to achieve for them.

In Australia, there are four basic different types of rams (with different selection criteria) used for different production systems. They are as follows :

1. Wool sheep: Selection criteria concentrates on fleece weight, micron and handle, with a small amount of emphasis on meat charactistics.
2. Dual purpose: Selection criteria in a true dual purpose sheep should be a 50% for wool and 50% for meat and fertility. Unfortunately for many years too much emphasis was placed on wool “type” and not enough on measured performance for wool, meat and fertility. The end result has seen these sheep perform poorly in both wool and meat
3. Terminal sheep: These sheep are used to cross with specially bred maternal ewes, prime lamb ewes or suplus merino ewes to produce prime lambs, all of which are slaughtered for meat. Selection criteria concentrates on live weight gain and meat quality. Rams can be selected for different production systems i.e. in areas with a short growing season, breeders will select rams that are fast growing and early maturing to product trade weight lambs (16 – 22 Kg carcass weight). In areas that have a longer growing season, lamb producers may select rams that produce heavy export weight lambs (22 – 28 Kg carcass weight). These lambs will be later maturing, and will achieve a heavy weight with a good meat to fat ratio.
4. Maternal Sheep: Selection criteria concentrates on fertility, growth rates, and milking ability. These sheep are used to cross with other maternal sheep or surplus merino ewes, and the resultant female progeny from this cross are used to produce prime lambs. The Coopworth is a maternal sheep, and has the distinct advantage in that it can be used to cross with the Merino, or be used as a self replacing prime lamb flock. These self replacing flocks usually mate the top 1/3 of these ewes to Coopworth rams, the ewe lambs are retained for the flock, and the wethers are sold as export lambs. The other 2/3 of the Coopworth ewes are mated to terminal sires to produce either trade or heavy export lambs.

Selecting Coopworth rams:

1. Selecting a Breeder: The first step is to decide which stud you wish to purchase your rams from. I would select a stud that has a good number of ewes, is run under commercial conditions, is performance recording, and is making good measured genetic gains. Larger studs usually have a greater genetic diversity hence there are less problems with inbreeding. Fortunately the above criteria applies to most Coopworth studs in Australia.
2. Breeding Objectives: The next step is to decide what genetic attributes you wish to put the most emphasis on. The Coopworth breed uses an index (growth 43% fertility 34% wool 16% muscle 5% and fat – 1%) to rank its animals. This index is based on financial returns and compares all animals within the breed. It is a very useful tool to use when selecting rams. The individual breeder may wish to place more emphasis on particular traits, so they will select animals that are high performing and well above average for the selected traits. It is always hard to decide which rams you can afford. If you have an average flock, a ram with an index of 112 will give you a 6% genetic and financial gain, whereas a ram with an index of 120 will give you a 10% gain.
3. The final step is to do a physical check of the ram.

(a) Head: I start with the head. The ram’s teeth should meet the upper pad evenly, and should be about 6mm back from the front of the pad. If they are any further forward, as the sheep ages, the teeth will move forward in front of the pad. I do not like too broad a head, as this may cause lambing difficulties.

(b) Shoulders & Back: I then go to the shoulders and back. The shoulders must be narrower than the hips and the shoulder blades must be placed below the backbone. The rams should have a long straight back, with no dip behind the shoulder. A slight wedge shape from shoulder to hip will usually see the female progeny have fewer lambing difficulties.

(c) Legs: The legs must be well placed and relatively straight. The hind legs should not be too far back on the pasterns.

(d) Feet: The feet should be black, broad and well splayed with no excessive horn growth, and placed on the ground evenly.

(e) Fertility: The testicles must be large and firm with a slight sponginess. If you are not sure how to tell wether a ram has good testicles and penis, talk to someone who does know, because they are the most important parts of the ram. The whip on the end of the penis must be in place and undamaged. Shearers can sometimes inadvertently cut this whip, and it can result in an 80% reduction in the fertility of the ram.

(f) Wool: The wool must be white and even for type over the sheep. My own personal preference is for a finer and shorter type wool. Whilst these sheep will cut less wool, the skins from their lambs usually command a better price under our skin selling system, and I find less difficulties with casting of the ewes.

I prefer a taller, longer sheep to a small, well muscled sheep, as I find them to be easier care.

Remember: The rams that you purchase today, are the foundation for the profits you make in the future.