Milk yield from dried hay better than anticipated in 2021

Milk yield from dried hay better than anticipated in 2021 - cows can adapt their metabolism

(Dr Edmund Leisen, North Rhine-Westphalia Chamber of Agriculture, Katharina Weihrauch, Hesse Department of Agriculture, Peter Kunz, Switzerland)

Cool, damp weather impedes hay production, especially in the Atlantic climate. Good quality hay can therefore only be reliably produced with drying systems. Cows can adapt their metabolism to a low supply of energy and proteins and still remain healthy.

Many farms have toyed with the idea of installing a hay drying plant in recent years. Hay groups for the systematic production of pasture milk have formed in various regions. And not only for cheese production. Some began this year. On 1 November from 20:15 experienced farmers and newcomers will report on their experiences during an online farmers' get-together: How did the harvest and the subsequent drying go and how well does it perform as a feed?

Drying in the field: particularly difficult in the Central Uplands and NW Germany

This year was once again a real challenge especially for farms relying exclusively on drying in the field. After turning the grass many times, almost nothing but straw was left. No wonder that cows found it difficult to produce milk from this. My experiences from previous years: The average herd milk yield can drop to significantly below 10 litres per cow. A challenge both for the animals and for the farmer's bank balance. Freshly calved cows and cows with their first calves are most affected. Looking back shows that  nothing has intrinsically changed. In earlier years, hay formed the basic fodder for winter feeding across all regions. The quality was usually poor and so was the milk yield, which was around 2,900 kg ECM/cow in the mid-1930s. One key reason for the poor quality of the fodder is to be found in the damp climate with the influence of the Atlantic and the fact that drying conditions in the central upland areas are inadequate in most years to produce a significant amount of hay of a quality good enough to use. Often the next rain shower arrives before the hay is dry.  Conversely, in the drier and sunnier conditions in Southern Germany, the drying conditions are significantly better.

Table : Field days available for drying in the field at the  1st cut

 

Source: Pfau 1971

(1) Frequency with hay drying weather within an envisaged period of 10 days

 

This is why nowadays farmers in Northwest Germany predominantly prepare silage for indoor feeding. The majority of farms also produce some hay for the calves and also some for the cows because well produced hay in itself offers good quality. However, the prerequisite for a good hay harvest is that the ground must first be dry and a minimum of 3.8 to 5.2 dry days in the field should follow the cut. Ten days should be available for an entire cut, which in the Central Uplands and on the Northwest German Plain can be expected only in 13 to 20% of years.

Later 1st cut,  2nd cut  richer in energy

The first cut this year was very late even for silage production. On most farms, the grass was not cut until the end of May/beginning of June. It has been so late only once (2013) in the last 23 years, during which the harvest dates on organic farms have been recorded as part the Organic Farming in North Rhine-Westphalia Project. Those producing hay had to wait a further 10 to 14 days for the ground and air to be sufficiently dry. At this point in time, the fodder was understandably already more intensively aged. No wonder since it was on average only around 5 MJ NEL/kg DM, a value, which has been achieved on average over the past years even in hay samples from drying in the field. Only those already able to cut at the end of May or located at altitude in the Central Uplands achieved 5.73 MJ NEL/kg DM.

It became even more difficult if the fodder went into storage before the harvest. Then even crops rich in clover or lucerne quickly develop an unpleasant smell and in extreme cases can no longer be used as feed. In this case, the choice of variety must be based on sufficient stability. As a rule, Italian lucerne varieties are less stable than German varieties.

The second cut  occurred on average 47 days later and in terms of energy was comparable to the early first cut, however on average it was at least richer in protein.  13.5 rather than 11%.

 

 

Hay milks better than analyses would have us expect

The analyses of the first cut  were disappointing owing to the time of cutting and yet no other result could be expected. However, the hay seemed to feed better that anticipated. Reasons for this:

1. Well-produced hay is eagerly consumed. In direct comparison with wilted silage: plus 1–4 kg dry matter (Kaufmann and Zimmer, 1970). One reason may be the higher sugar content. Another reason is the palatability. The acid content in silage inhibits consumption. The higher feed intake can at least in part balance out lower content.
2. The use of hay is possibly underestimated. A ten-year trial at the Plantahof Institute in Switzerland is illuminating. During the winter, 38% of cows fed with hay dried indoors yielded some 8,200 kg ECM/annum. In addition, the ration was composed of 42% maize silage and 20% grass cobs (in each case related to dry matter). In the summer, 2/3 of the herd went to pasture. In 2006, I had three hay samples sent to me: 5.6 MJ NEL/kg DM and thus consistent with the mean value over many years at the Plantahof. But not enough to explain the milk yield.

 

Metabolism adjusts to low energy and raw protein supply.

8,200 kg ECM/cow and year in the roughage (roughage herd compared to performance herd, each with some 40 Brown Swiss cows) was not to be anticipated from this. There are two main reasons for this astounding result.

1. Excellent quality is needed in all the components of the ration.
2. When cows are constantly fed for weeks and months with limited amounts of raw protein and energy, their metabolism adjusts and converts the energy and protein consumed more efficiently.

Negative results for energy and raw protein

Energy: If energy supply remains low, the metabolic rate is reduced. The cow produces less heat to save energy. Thus, more energy may be used to produce milk. Example from the Plantahof herd: At an actual milk yield of 33 kg, increased feeding resulted in energy intake for only 30 kg (milkenergy balance: -3.0 kg milk).

Raw protein: The metabolism compensates for a lower raw protein content in the ration by eliminating less raw protein in the faeces, urine and milk. Example from the Plantahof herd: At an actual milk yield of 33 kg, increased feeding resulted in an intake of convertible protein for only 24.5 kg milk (convertible protein balance -8.5 kg milk). The cow adapts her metabolism to a considerable extent even with raw protein. In comparison with performance herds managed in parallel (some 10,000 kg milk, 5.4 kg concentrated feed, no negative energy and protein balances): 12% less protein in the milk, urine content in the milk and raw protein volume in the urine 50% lower respectively, raw protein volume in the faeces 28% lower. They were also obviously healthier: 19% replacement rate in comparison with 35% in the performance herd. Consistent with our own analyses over many years: 4.7 years useful life with 106 days in the year with 150 mg urine per kg milk; with "balanced protein supply" only 3.8 years.

It would seem that  the raw protein content in the ration cannot be reduced at will. If the raw protein intake is too low, the milk performance and milk protein content drop dramatically and digestion of the ration as a whole is degraded. In the conditions referred to above, however, the required intake is significantly lower than the feeding standards lead us to expect.

Münster and Kassel, 29 October 2021