This has raised the obvious query: “Why not use liveweight (LW) change as the critical measure of stock performance and wellbeing, rather than CS?”
This is particularly relevant to the Demonstration Farm as it is well-equipped with yards and scales to enable speedy and efficient measurement, further helped by staff and cows being well used to, and experienced with, the procedure.
The big positive for this is that when it comes to publishing results they are objective – they have been obtained by a machine, not by human judgment, and so cannot realistically be disputed. In contrast CS estimation is subjective. It is an estimate made by one or more individuals and its accuracy and reliability will be dependent on the knowledge, skill and experience of the assessor(s).
Another significant factor will favour weighing. CS is an expression of the external fat covering on the cow. In essence, this is the body reserve of the cow. When excess feed is available she adds to it; in times of inadequate feed availability, she breaks it down and draws on it for energy to keep the vital functions operating.
This is not the only body fat in an animal. There is also a large amount of internal fat around the vital organs, protecting them. If starvation continues, after all external body fat is used the animal will draw on this internal fat to survive. Finally, as a last step before death from starvation, it will break down muscle tissue. What this means is that an emaciated animal, with a generous feeding regime restored, may well be laying down muscle and internal fat and exhibiting no improvement whatsoever in CS, but making significant gains in LW, and hence wellbeing.
Compelling reasons to use liveweight as the critical indicator of animal wellbeing at the Demonstration Farm? Maybe not. First, it would be fair to say that no cow on this farm would ever be allowed to get so emaciated that she would have to start mobilising internal body fat and muscle in order to survive.
The other argument of the superiority of objective measurement also has its flaws. First, weighing scales, like any other piece of equipment, can malfunction – and this has happened more than once at the Demonstration Farm. This need not be considered a major drawback, because the scales can be checked before beginning by weighing of a few bags of urea, or meal, or anything else of a known weight. This can also be repeated during the process, particularly if large numbers of animals are involved.
‘The cost of setting up a reliable weighing system and the hassle of using it often enough to justify its use, compared with any benefit it contributes, makes it a fairly dubious proposition.’
The inaccuracy factor that is not so easily overcome is the one of gut fill. A cow taking in 18kg drymatter (DM) at 15% DM daily, will have consumed 120kg of green material. It is thus not surprising that gut fill can vary by more than 50kg over the course of a day. The only practical way of trying to eliminate this problem is to have the herd on a consistent grazing pattern, and to weigh them at the same time of the day, but this still won’t give 100% accuracy.
It can thus be seen that neither system is perfect. Both have their strengths and weaknesses, so the best compromise is the traditional belt and braces approach – and use both, as we do at the Demonstration Farm, though I would hesitate to suggest this would be appropriate for the average commercial farm.
The cost of setting up a reliable weighing system and the hassle of using it often enough to justify its use, compared with any benefit it contributes, makes it a fairly dubious proposition. This is especially so when the condition score option is freely available and easily implemented at no cost. The objection of the lack of objective measurement certainly can be minimised. There are plenty of “how to” guidelines around, including photo descriptions (Go to the Dairy NZ website). Practice will quickly increase skills and enable you to get your eye in quickly and consistently.
My simple technique for getting the eye in is to use the knowledge that cows should be at a minimum of CS 5.0 at calving, so work the system in reverse. Sort out a few cows you consider to be in the ideal condition for calving – that is, CS 5.0. Using them as a benchmark, grade all the others up or down accordingly
My other technique has got nothing to do with scoring condition– it’s more a matter of arriving at a conclusion without having to define how it was reached. If I walk into a mob of dry cows in the middle of winter and the first impression is a preponderance of ribs showing, then the inevitable conclusion has to be that condition is inadequate.
Being a subjective assessment, condition scoring is obviously much more of an art than a science. This brings in the traditional values of stockmanship which are difficult, if not impossible to teach.
All condition scoring does is formally establish a level of animal wellbeing. This provides a base from which progress can be recorded and monitored – either improvement or deterioration.
This is the important facet of condition scoring – the change, not the absolute. The essential operating factor then is consistency. It’s not the accuracy of the score allocated, but rather that the next assessment uses the same criteria and accurately reflects the change, if any, that has occurred.
It matters little if the CS was assessed at 4.5 when it was really 4.6, providing the next assessment is assessed at 4.7 when it was actually 4.8. It could be argued that weighing, as an objective operation compared with condition scoring, will provide the required degree of consistency and stability. This is true to an extent, but gut fill can be an enormous variant so it is vital to weigh under the same conditions each time, in which case the hopefully minor unders and overs will balance out over the whole mob.
‘All condition scoring does is formally establish a level of animal wellbeing.’
This advantage is substantially removed when it is compared with the system of running the whole mob through a race, condition scoring all the cows individually, then averaging the result. This is much more time-consuming and intrusive than simply eyeballing the mob in the paddock and making a snap judgment on average condition score. The big problem is that when the cows are being seen daily, or close to it, it is difficult to spot subtle changes and the fact that they are accumulating longer term fails to register accurately.
Coming back to the subjective assessment factor however, there is one piece of modern technology that can be of great help. Most farmers carry a cellphone in their pocket. It is a simple matter to identify a few placid and photogenic cows and regularly photograph them from the traditional condition scoring view – rear and back. This can be compared with the same view taken a week, a month, a year, or whatever, previously – surely the perfect blend of the subjective and the objective.
