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3.6. Moulds and Mouldy Feeds
During the conservation and storage of forages and grain, there is a risk that moulds will form on the feed
and cause a number of problems for cattle to which it is subsequently fed. In general terms, the nutritional
value of mouldy feed is reduced by their presence, as the moulds convert and utilize plant nutrients for their
own growth.
Mouldy feeds can be very dusty due to the presence of mould organisms and spores. When the dust is inhaled,
a type of fungal pneumonia may develop. This type of pneumonia is diicult to treat. Some spores may pass
through lesions in the rumen wall and are carried by the bloodstream. The spores may settle in the pregnant
uterus causing uterine infections and mycotic abortions. Some moulds also produce toxins which can be
extremely potent. These toxins can cause abortions or weak, deformed calves. Other symptoms include
internal bleeding, vaginal and rectal prolapse, gangrene- like symptoms, and paralysis. Estrogenic compounds
produced by some moulds may afect lactation and reproductive cycling.
Some toxins are extremely poisonous to cattle. Ideally, mouldy feeds should not be fed to pregnant or lactating
cows. Diluting moulded feeds with good quality feeds may help reduce the potential for problems. An adequate
supply of vitamin A should also be provided for cattle if mouldy feed is used.
Figure 3.7. Principle of fodder conservation.
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Cold Winter Climates
3.7. Cold Weather Impacts on Feed
Management 3.7.1. Ration formulation for Cold Weather
For most very cold winter climates, an assumed midday ambient temperature of -20
o
C should be the basis for determining the basal dietary energy requirement of
the ration during the coldest winter months. Thereafter, the ration can be balanced for speciic growth targets
for diferent classes of animal, and pregnancy status of mated cows. When this temperature target is adopted,
there is suicient scope to manage sudden and dramatic drops in temperature by adjusting the energy
concentration in the ration using increased quantities of grain. When practiced in conjunction with the use of
3 to 7 day weather forecasts, planning for the onset of poor weather conditions can be implemented, and can
allow for the safe introduction of higher levels of grain in the diet.
Sudden drops in temperature during the winter months will cause cows to consume more feed as a physiological
response to the cold conditions as the cows react and demand more energy. Feeding cattle low quality
roughages in winter enables the animals to generate heat through the process of ‘heat of digestion’. This
heat alone is not suicient to meet the animal’s energy requirement, and therefore the energy component of
the ration must be suicient to enable the animals to meet their metabolic requirement and growth targets.
To meet their increased energy requirement in very cold weather, cattle fed poor quality feeds such as straw will
attempt to consume more than they are able to digest and there is a risk that the rumen may become impacted
and cease to function properly. This can lead to the death of the animal. Under these conditions, straw fed
to cattle should not be processed through a mill or tub grinder, as this will encourage a greater intake of the
straw and rumen impaction, particularly when sudden drops in temperatures occur.
Extremely cold temperatures are more adequately managed by adjusting the energy concentration in the
diet by increasing the quantity of grain or pellets at a rate of 0.5kg per head per day for every -5
o
C drop in temperature below -20
o
C at midday. For example, if the afternoon air temperature is forecast to be -35
o
C, then an additional 1.5kg of grain per cow should be provided.
Extreme care is required with sudden increases in grains in the ration as the risk of acidosis grain poisoning
increases substantially. It is a good practice to divide the grain over morning and night feeding to limit the
chances of grain poisoning. If a cold snap is forecast, small extra amounts of grain should be fed for a couple
of days before the weather change is expected.
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4. Cattle Health and Welfare
4.1. Observational Skills
Kategori