Tips for Legume Pasture - Lucerne

Lucerne and Merino’s go together like a horse and carriage; a wonderful working marriage!  Lucerne is the most productive of all perennial pastures legumes and it is hardy and persistent to boot.  

This explains why more land is planted to lucerne than any other perennial pasture legume in SA.  If lucerne did not have a bloat problem, there would be little need to use alternative perennial legumes.   Many farmers complain about grass invasion in their lucerne lands.  This is actually an indication that the soil is poorly mineralised.  Lucerne is particularly dependant upon calcium and phosphorous.  Liming to correct pH is most certainly no assurance that calcium levels in the soil will be built to optimize; very often they will fall far short of this all important mineral.  Huge – very costly and wasteful - applications of super phosphate are needed to build soil P to the desired level.  For this reason most farmers don’t apply sufficient P, consequently lucerne suffers from P hunger. This reduces its vigour, thus giving grass weeds the competitive edge.  In the long run, building P with rock phosphate is far more effective and less costly.  For top yields and the production of high quality lucerne, soil minerals should be fully balanced according to the Albrecht model.

Johne's Disease (paratuberculosis) - signs and prevention

Johne's Disease (pronounced "Yo nees") is a disease that affects the intestines of mostly ruminants. It is caused by a hardy bacteria called Mycobacterium paratuberculosis.

Johne's disease is most commonly observed in dairy cows, but may also affect beef cattle, sheep, and goats.

The strain that affects sheep is different than the one that affects cows, though there is an intermediate strain that sheep are susceptible to. While cattle experience diarrhea, in sheep, Johne's tends to be a wasting disease. Control of the disease in infected flocks is difficult due to the lack of a reliable live animal test. Vaccination will reduce the number of clinical cases in a flock, but will not prevent all animals from becoming infected. Colostrum from other sources (cows, goats) may be a source of infection in sheep flocks.

What are the signs of Johne's disease and how can I tell if my flock has Johne's disease?

This disease is hard to detect. The signs of Johne's disease are vague and months can pass after infection before they appear. Weight loss in animals with a good appetite may be the only indication as diarrhea is not a common sign in sheep, unlike what is seen in cattle. Infected sheep may appear unthrifty and wool break/poor fleece condition may also be noted. The signs of Johne's disease can be confused with the clinical indications of other conditions such as parasitism, OPP (ovine progressive pneumonia), CLA (caseous lymphadenitis) or malnutrition. Of course, more than one problem may be occurring - for example, sheep eventually succumbing to Johne's disease had improved clinically after treatment for parasites. Because of the slowly progressive nature of the infection, signs of Johne's disease are usually not seen until animals are adults.

How do sheep get Johne's disease?

Johne's disease typically enters a flock when an apparently healthy, but infected animal is introduced. This animal contaminates the premises (feed, ground, water) by shedding the organism in its manure. The organism is then ingested by other sheep. Lambs are thought to be most susceptible to infection and their suckling manure-contaminated teats are another route of infection. It is also possible that a ewe in the later phases of the infection can shed M. paratuberculosis into her milk and colostrum, thus transmitting it to her lambs.

How can you prevent your animals from getting Johne's disease?

The best way to avoid this chronic infectious disease of course is to be as certain as possible that animals brought into the flock are not infected with M. paratuberculosis. Johne's disease test-negative flocks are the best sources of animals for purchase. Since many flock managers have not yet test for the infection, assess the entire flock (not just the animals you intend to buy) for body condition. Ask the owner about the cull rate and common cause for culling - how many animals were thin/unthrifty for no confirmed reason? Check the body condition of the dam of lambs you intend to purchase and have her tested if you have suspicions (tests on sheep less than one year old are not likely to be informative unless exhibiting signs of the infection).

Following general rules of sanitation are helpful in blocking transmission of the infection. Feeders and waterers should be designed to minimize the likelihood of fecal contamination. Lambing should occur in clean, dry areas. Animals with weight loss or diarrhea should be segregated from the rest of the flock and tested.

Wool Sheep Production Plan

All successful wool sheep enterprises work according to some form of wool sheep production plan.  The following is a crisp reference to management practices during the different production stages that may have an influence on the profitability of wool sheep farming.  Consider them, identify possible risk areas, structure a plan and away you go!

Ewes - Conception criteria

Maximum ovulation occurs during the autumn mating season when ewes show natural heat.

The heat cycle of ewes is 16-17 days with the result that a mating period of 34 days is sufficient.

Flushing has little effect if applied longer than four weeks before mating.

The condition of the ewes at the time of mating is considered the most important factor in achieving high ovulation rates, regardless of how it is achieved.

Extremes in nutrition during the mating period should be avoided and ewes should, in the first month of pregnancy, be kept at a constant feeding level.

Embryos in the pre-implantation phase (from conception to day 15) may be lost in ewes that are in a poor condition or when subjected to extremes of under- or over-nutrition.

The same applies during the implantation phase. (Day 15-16 to day 30 after conception)  Losses during this period have a wider range of effects on pregnancy.

These effects include:

o    Increases in the proportion of ewes which return to the ram at more than 19 days after mating

o    A reduced lambing percentage

o    Small lambs

Mid and late pregnancy

Fetal growth during the second and third months of pregnancy is slow with rapid gains in the last trimester

The feed intake of ewes is normally adequate in late pregnancy.  Ewes mobilize their own body reserves for utilization by the fetus.

o    As the number of fetuses with extra nutritional demand increases, ewes will find it difficult to compensate by increased voluntary intake.

o    Under-nutrition of ewes, in late pregnancy can reduce weight at birth, particularly in the case of twins.  It is therefore advisable to scan ewes for twin identification 42 days after ram withdrawal.

A low birth weight disadvantages lambs in almost every way.  70 % of the unborn lamb’s development takes place during the last six weeks of pregnancy.  Such ewes should have a weight increase of between 15 and 20% (150 – 250 g/day for ewes with a single fetus and 250-350g/day for ewes with twins is advisable).

The following results can be expected:                                                       

Energetic lambs (birth weight 3,5 – 5,5 kg)

Optimum udder development for maximum wool production is secured

Less tender wool

Pregnancy disease is prevented

Lactation

Optimum lambing percentage is achieved by lambing in smaller groups and camps.

Ewes carrying twins should lamb in groups of no more than 30 while single-lamb groups can be increased to between 50 and 80 ewes.

It has been found that lamb mortality increases by 7,5 percent whenever the flock numbers increases by 50 ewes.

Lactating ewes should never lose more than 25-50g (singles) and 60-100g (twins) body mass per day.

In the first month of lactation a ewe requires considerably greater amounts of energy and protein than the amounts needed in late pregnancy.

Proper feeding will result in:

o    Maximum weight gain by twin lambs – during the first three weeks of lactation, lambs are completely dependent on milk.

o    Maximum milk production.

o    Ewes are in a good condition when egg-cells are formed. An egg-cell formed today will be ready to be fertilized 180 days later.

o    The development of wool follicles for a stable wool production is supported.

 

Lactating ewes in a good condition can be mated with great success.

Weaning

Milk production peaks approximately 3 to 4 weeks after birth.  Keeping this in mind it is often, during adverse conditions, cheaper to feed the lamb only instead of both the lamb and the ewe.

Wean lambs in camps to which they are familiar.  A few older ewes retained with newly weaned lambs should reduce stress.

During periods of drought lambs can be weaned as soon as they have intake of between 200g and 250g creep feed per day.

The proper feeding of young sheep, especially during their first 6 months is advisable – grow them out well!  Their future ability to produce is increased by this practice.

Flock composition and selection practices

In order to maintain a high quality standard throughout the flock it is important that selection practices and the composition of the flock be addressed as a unit.

A breeding flock must be replaced annually by between 30 and 35% maiden ewes.  If certified pregnant a 25% replacement will be sufficient to maintain a flock.

To explain this, one must note that in theory any flock should have 5 age groups of 20% each.  In practice you will experience losses with the result that the oldest group in a flock seldom retains more than 16% of the original input.

First selection

This practice allows the replacement of ewes 6 years and older.  These ewes are normally less productive and tend to experience more udder and foot problems.  It is impossible to identify these ewes by their teeth only.  The use of color tags to mark the different age-groups is practical.  Age groups can also be identified by earmarks at a labour cost only.

Second selection

Examine all lactating ewes when the lambs are docked to identify those who lost their lambs as well as those with udder abnormalities.

The wet & dry selection method can be applied.

This inspection should be carried out at approximately 4 to 6 weeks after lambing.  It entails that udders be examined and that ewes with dirty teats be culled.  Mistakes can be made. It is a good practice to identify the presumably skipped ewes and to leave them in an adjoining camp while retaining the lambs close by. Your mistakes or the ewes with the lambs will not wander off too far.

If this method is followed correctly, you should, in 10 years time, have increased your weaning percentage by 20%.

This selection practice means money and ensures a healthy flock composition.

 Third selection

Eventually you should have excess ewes and numbers to play with.  In such a case a good practice will be leaving the runts in the flock at weaning.  Wet & Dry these ewes in a week's time and cull both ewe and lambs – this time the ewes with clean teats.

Fourth selection

Identify and discard maiden ewes with sub-standard wool and conformation problems.  This fourth selection method applies when your flock counts are sustainable.