Effective lamb management is one of the main contributors to success in sheep production. High lamb mortalities not only result in fewer animals being available for slaughter, but also affect the sustainability of a farm by resulting in fewer replacement animals being available to keep the enterprise going.
Instead of letting nature take its course, management can be made easier if ewes are grouped together and allowed to lamb at around the same time. When deciding on the timing of lambing, the two major considerations are the availability of labour, and the availability of food.
“The lambing season should fit into your production schedule. In other words, it should fall outside holidays and the harvesting or planting season, and at a time when there is sufficient grazing or pasture to help ewes regain condition after lambing,” says Dr Josef van Wyngaard, technical manager at Voermol Feeds.
The lambing environment is another significant influencer of lamb survival. The options are basically in the veld under extensive conditions, in smaller camps, or in lambing crates or pens.
Van Wyngaard points out that lamb mortalities average around 5% in lambing crates in comparison with 10% in small camps and 15% or more under extensive conditions, depending on external threats such as predation.
Lambing crates have a number of other advantages. The small space enhances
bonding between ewes and lambs, which in turn prevents lambs from wandering off and dying, and it offers shelter against predators, extreme weather and theft. The system also makes it easy to pair ewes with their lambs for proper record-keeping.
The crates need to be kept dry and clean, as pathogens build up faster in lambing crates than in camps because of the higher concentration of animals. Farmers can address this by limiting the time in crates to five days before and five days after lambing, says Van Wyngaard.
Alternatively, the ewes can lamb in small camps near the crates and be moved with their offspring to the crates shortly after lambing.
While sunshine is the best disinfectant, the cubicles should be washed and then covered with hydrated lime before straw bedding is added for the next group. The area needs to be well ventilated to prevent respiratory problems, but still provide shelter from the wind and cold.
The umbilical cords of the lambs should be treated with iodine as soon as possible after birth to prevent infection.
The ewes and their lambs should be moved from the crates to small groups before being introduced to larger flocks.
The main drawback of lambing crates is their cost, but this is more than justified by the higher lamb survival rate.
To maximise the return on investment, Van Wyngaard advises farmers to divide the flock into two or three groups, each with its own lambing period, rather than try to handle the entire flock in one go once a year in a single huge facility. The crates can be used as a ram test station between seasons. Some farmers only use lambing crates for ewes that carry multiples.
Van Wyngaard divides the feeding of lambs into three phases, with the first being linked to colostrum. To help them build immunity against pathogens, lambs should receive about 210ml of colostrum per kilogram of bodyweight within the first 24 hours of birth.
Lambs that receive too little colostrum will grow poorly and be weak and more vulnerable to diseases, he says.
Weak lambs can be dosed with 100ml colostrum (saved from ewes that have already lambed) three to four times per day for the first two days of their lives. Colostrum can last for up to seven days when stored in a fridge and up to six months when frozen.
It should be warmed to room temperature before being given to lambs, and not above 37°C, as this will destroy the antibodies associated with its immunity-building benefits.
To prevent deterioration in quality, colostrum must also be used within an hour after collection or after being warmed. In the absence of colostrum, farmers can buy commercial mixes or mix their own by using 500ml full-cream dairy milk, 120ml cream or three tablespoons of cooking oil, one egg, and one tablespoon of lactose or sugar.
These alternatives do not contain any antibodies, however, and will not offer the same protection against prevalent diseases as colostrum does.
Lambs are highly dependent on their mothers’ milk up until weaning, so farmers must ensure that the ewes are in good condition.
Licks or rations containing high levels of bypass protein are especially important during the last six weeks before lambing; this will ensure good-quality colostrum and milk production, maximising the chances of lamb survival.
“The type of rations will depend on the type and quality of feed available on the farm, and whether the ewes are carrying multiple lambs or single lambs. Various companies offer commercial premixes to help ewes maintain and regain condition,” says Van Wyngaard.
He points out that the milk production of ewes usually peaks four weeks after lambing. Thereafter, lambs will increasingly be given creep feed.
“Lambs younger than 30 days have a feed conversion ratio of 1:1, meaning the intake of 1kg feed will result in a weight gain of 1kg, with the feed conversion declining as lambs mature. To alleviate the impact of reduced milk supplies on growth, lambs can be supplied with creep feed to unlock their full genetic potential,” says Van Wyngaard (see Table 1).
|TABLE 1: WEIGHT GAIN IN LAMBS
|Age in days
|Mass in kilograms
|Feed conversion ratio (kg/kg)
|0 – 42
|4,5 – 15
|42 – 60
|60 – 80
|20 – 25
|80 – 100
|25 – 30
|100 – 120
|30 – 35
|120 – 140
|35 – 40
|140 – 160
|40 – 45
|Source: Dewald Vosloo, 1982
Lamb creep feed is a high-energy, high-quality, protein-dense ration formulated to promote early rumen development in lambs and maximise their weight gain over a short period. The creep feed should first be given to lambs from seven to 10 days after birth, initially to get them used to it, but also to stimulate rumen development to allow maximum intake by the time they reach three weeks of age.
The earlier development of the rumen brings forward the weaning age and reduces weaning stress.
“Lambs are usually weaned when they weigh more than 20kg, which is reached at roughly three months of age in extensive production systems and around two months in an intensive eight-month production cycle. When creep feed is provided, a target weight of 25kg to 30kg can be reached in 56 to 70 days for wool breeds, and even sooner for meat breeds,” says Van Wyngaard.
Lambs that receive creep feed may also be sent to the market up to 50 days earlier than those left on pasture or that only receive ewes’ milk, which in turn enables farmers to stock 10% to 20% more ewes by freeing up valuable food sources. They also perform better in feedlots, as they are already used to energy-dense feeds.
In addition, creep feed has been found to have a positive impact on ewe reproduction.
“Ewe lambs subjected to feed stress during the first couple of months of their lives have been found to have a lower ovulation cycle and to produce fewer lambs during their lives than those that never experienced feed stress. This is probably also why the lambing percentages of ewes that received creep feed when they were lambs are higher on average than the percentages of those that did not,” explains Van Wyngaard.
Supplying an all-purpose lick will not help, as lambs have a higher nutrient requirement than mature animals. Creep feed, for this reason, should contain at least 16% protein and have as high an energy content as possible.
Grain is an excellent source of energy and highly digestible, and also helps to stimulate rumen development through the formation of butyric and propionic acids. Roughage, in contrast, is a poor producer of these acids and in effect not a great rumen developer.
Lambs also have limited rumen capacity to unlock the nutritional value of roughage. High-quality lucerne is the roughage of choice and should be included at 10% to stimulate intake.
According to Van Wyngaard, an example of a balanced lamb creep feed mix would be 150kg Voermol SS200 (V8592), 150kg Voermol Procon 33 (V12701), 550kg maize meal or barley grain, 100kg milled lucerne hay and 40kg Voermol Molasses Meal (V1995).
This mixture contains feed additives to promote weight gain and prevent bladder stones, acidosis, bloat and coccidiosis, and also has various essential macro- and trace minerals as well as vitamin A to improve animal performance.
On average, lamb creep feed intake can vary from 15kg to 25kg per lamb over a two- to three-month period (see Table 2).
|TABLE 2: LAMBS’ CREEP INTAKE
|Age in days
|Intake (g) per lamb weight (kg)
|Source: De Villiers et al, 2002
The entrances to the creep pen should be small enough to prevent ewes from pushing their way in. Each opening should range from 20cm to 25cm in width, or 18cm with thin ewes, and 40cm to 50cm in height. Alternatively, large irrigation pipes can be used with holes large enough for a lamb’s head to access creep feed in the pipe.
In a further effort to prevent coccidiosis, creep feeders should be designed in a way that prevents lambs from standing in the troughs.
The feeders should also be long enough to prevent competition between lambs, with 5cm feeding space per lamb being optimal and 2,5cm/lamb the minimum.
Email Dr Josef van Wyngaard at [email protected].