“The eye of the shepherd fattens the lambs”
By Dale Engstrom, MSc, Pag
I think I do a pretty good job interpreting feed and water reports, developing specifications for commercial feeds and balancing rations for my clients. During my farm visits, I look the feed and flock over closely and make recommendations for possible improvements. However, I am only on the farm 2–4 times per year, so I rely on feedback from the shepherd to put the feeding program into practice, and make it work and be profitable. Successful shepherds have good powers of observation and keep good records. The combination provides me with the information I need to evaluate the feeding program I have put together.
Here are the production records that relate to sound nutrition of the flock:
- Body condition score (BCS). BCS is a direct result of the energy levels of your rations. Protein and other nutrient deficiencies can negatively impact the amount of energy extracted from the feed. Learn and use the BCS system and record the results of at least a representative sample (10–20%) of the flock every time they are run through the handling system.
- Birth weight of lambs. Singles will be heavier than twins or triplets, Suffolk lambs will weigh more than Dorset lambs, but you should develop an average weight for your biological type that tells you if everything has gone well in the last 6 weeks of pregnancy. If the average birth weight drops noticeably one year, look at the energy and protein levels in your late pregnancy ration and the body condition score of your ewes. Some prolific flock owners have a minimum threshold birth weight they use to cull lambs that are not likely to thrive or survive.
- Abortions and stillborn lambs. These losses are most likely related to disease, but severe vitamin and trace mineral deficiencies may be involved.
- Pre-weaning mortality. Pre-weaning deaths can be caused by a variety of disease and management factors, but when trying to determine the problem and the actions to be taken, don’t ignore nutrition, especially those nutrients related to a healthy immune system.
- Weaning weight. Weaning weight is largely a function of milk production in the ewe, which is heavily impacted by nutrition before and after lambing. Ewes need to be in a BCS of 3–3.5 at lambing to have the potential to milk well. They can access some needed energy from body fat to support lactation, but they need adequate dietary protein and other nutrients to maximize milk yield.
- Days to market or average daily gain. Post-weaning growth rate in lambs is obviously impacted by nutrition, but genetics is also a large component.
- Pregnancy rate. Fertility is a function of body condition, ram power and length of breeding season. Nutrition impacts the rate through both the ewe and the ram.
- Prolificacy. The number of lambs born per ewe is a function of biological type and nutrition. Aim for a BCS of 3- 3.5 at breeding to maximize the number lambs born. Ewes below 3.0 will benefit from flushing for 2 to 4 weeks prior to breeding.
Two final points:
Did you notice how many times body condition score was mentioned? This is one of the best indicators of a good nutrition program and one of the easiest to do. Learn this technique and practice it often. Here are the annual targets for BCS:
- Breeding Ewes: 3–3.5
- Breeding Rams: 3.5
- Lambing Ewes: 3–3.5
- Ewes at end of Lactation: 2.5
I have avoided providing hard numbers for the indicators listed above because there are large differences between breeds and individual operations. You need to develop meaningful targets that are suitable to your sheep and farm resources with maximum profitability as the goal. But where do you start? The GenOvis genetic evaluation program provides annual reports based on the information they get from participants. This data is from purebred flocks that are typically smaller in size than many commercial flocks, but it provides valuable data nonetheless. The table on the opposite page will give you some indication of what is normal for some of the measures.
The ‘eye’ of the shepherd, also known as good stockmanship, has long been recognized as a valuable tool in the profitable production of lambs. Today we know the eye is really a variety of tools and measurements that can be used to provide an objective analysis of the production program, and several of them are very specific to the nutrition part of the management system.
Dale Engstrom is a consulting ruminant nutritionist who lives in Lake Isle, Alberta.