Pasture management
Controlling pasture quality throughout the year requires forward planning and good management skills. The essential tools for success are:
- Good subdivision, well fenced blocks or paddocks
- A feed budget and a grazing plan for the year
- A method of accurately measuring kg DM/ha
- The use of electric fencing
- Scales for weighing stock
- Regular condition scoring of animals
- Maintaining a reliable water supply and good water quality
- A rain gauge
To build up a database, record information regularly. It will be a valuable tool for decision making in the future. Knowing how much pasture is available, along with pasture growth rates and the feed demand from stock allows you to make important decisions about:
When to graze and spell pastures so that they recover quickly, maintain quality and give greatest production
Finding the appropriate stocking rate for optimum pasture production and utilisation/ha
Feeding your sheep for maximum lamb and wool production
Good feed = quality wool
With merinos, the level of nutrition the animals receive has a direct effect on wool growth and quality of the fleece. The critical time for feeding pregnant ewes for maximum follicle development during foetal growth is from 60 days after conception to at least 70 days after birth.
Underfeeding ewes in late pregnancy will result in reduced lifetime wool production of a ewe’s progeny. A drop in ewe liveweight (as little as 2kg) is enough to cause wool tenderness.
Condition scoring is an effective way of assessing whether ewes are gaining or losing weight. The liveweight difference between condition scores equates to approximately 5kg.
Genetics predisposed to your environment
Sheep that are genetically fine will remain that way the majority of the time. Work with your ram breeder to identify sheep that will move to your environment and will perform to your expectations. Assessing Coefficient of Variation of Diameter (look for low CVs) on rams in conjunction with micron will help you identify sheep whose micron will remain stable. Your rams have the greatest influence in determining the average fibre diameter of your flock.
Calculating a feed budget
Feed budgets can be done on a paddock-by-paddock (or block) basis for individual mobs.
The first step is to calculate the total feed supply, the amount of pasture available.
To calculate this you need to know the paddock size or block area and the initial pasture cover and grazing residual.
e.g. Starting pasture cover = 1200kg DM/ha.
Grazing residual = 500kg DM/ha
DM available = 1200kg less 500kg = 700kg DM/ha
Paddock (block) area = 50ha
Total DM available = 50ha x 700kg DM = 35,000kg DM
The second step is to calculate feed demand (the total amount of feed required for a particular mob). This is based on the class of stock, their number and their daily feed requirements.
So 4000 mixed-age ewes, with an average bodyweight of 55kg, CS of 2.5. Daily feed demand to maintain body weight will need to be around 1.0kg DM/ewe/day, or 10 MJ ME/day/head (early to mid-pregnancy). Total daily feed demand for whole mob will be 4000kg DM x 1.0kg/hd = 4000 kg DM/day.
From both these totals the number of grazing days in the paddock can be calculated.
Total DM available equals 35,000kg DM. Total daily feed demand equals 4000kg DM.
Number of grazing days in paddock = 35,000kg DM, divided by 4000kg = 8.75 days.
Scanning allows single or multiple carrying ewes to be managed and grazed in separate mobs and fed accordingly. This is a more efficient use of pasture and supplementary feed.
Single carrying ewes require 1.5 times maintenance e.g. 1.3 to 1.5kg DM/day or 13 to 15 MJ ME/day. Twin carrying ewes require 1.75 times maintenance, e.g. 1.7 to 2.0kg DM/day or 16 to 18 MJ ME/day.
