November 24, 2008

Animal behaviour and welfare: Cattle Part 2


Cattle as ruminants: Grazing & milking: Feed intake

By Dr Clive Dalton

Cattle daily routine
  • Cattle digest fibrous feed in their three fore stomachs (rumen, reticulum, omasum) and then the abomasum, which is the true gastric stomach.
  • Digestion of fibre produces carbon dioxide, methane which is belched up or ammonia which is absorbed in the blood.
  • Cattle divide their day into periods of:
  • Grazing - taking in feed using their prehensile (grasping) tongue and bottom teeth. Feed goes into the rumen via the abomasum (honey comb bag) where heavy objects collect.
  • Chewing. The feed is chewed, formed into a bolus with saliva (100 litres/day) and swallowed.
  • Rumination. Here feed is given time to ferment in the large rumen.
  • Regurgitation. This is where the bolus is belched up again for a second mastication of 300 chews.
  • Swallowing feed again into the omasum (the bible) for final grinding.
  • Then passing into the abomasum for gastric digestion.
  • Idling. The cow stands appearing to do nothing. It's time of rumen fermentation.
  • Resting - lying down.
  • Drinking. A milking cow drinks on average 70 litres of water per day.
  • Sleeping. The cow sleeps for short periods during the night.
  • Dairy cows have to spend at least 8 - 10 hours/day grazing to meet their nutritional needs.
  • They are driven by "metabolic hunger" or the need to eat to meet their genetic urge to lactate.
  • A cow makes between 30,000 - 40,000 grazing bites/day.
  • Modern dairy cows have been bred for this kind of life which many Welfarists are now questioning as being too stressful.
  • If cows don't eat enough, they use up body reserves and get thin. This then triggers problems like anoestrus (non cycling) and farmers use intra vaginal devices and inductions (abortions) to control their breeding activity, both of which have negative welfare images in the marketplace.
Pictures of stomachs


Reticulum (honey comb bag)

Omasum (the Bible)

Abomasum (gastric stomach)

Milking effects on grazing routine
  • Non-lactating cattle and bulls have 3 main grazing periods from daybreak to mid morning, mid afternoon to half an hour after sunset, and then a shorter period about midnight.
  • Milking twice a day and removing cows from pasture has a large effect on cow behaviour e.g. long and slow milking routines force cows to graze into the night for an extra 1-4 hours.
  • Weather conditions will also force cows to change their grazing behaviour.

Feed intake. Getting dairy cows to eat more

Cow using tongue to sweep grass into mouth
  • The more a cow eats the more she produces, so having a permanently hungry cow is a legitimate aim of a herd manager.
  • So the first part of this challenge is to get the cow to take in a lot with each bite, so length of herbage is important for the cow to become satiated (feeling full) quickly, so she can lie down and digest her feed. A cow metabolises more milk when resting than when standing or grazing.
  • Cows cannot eat short pasture very effectively and about 20cm is a good length for optimal intake.
  • "Social facilitation" is also important which is where one cow triggers off the behaviour of the group. So which cow causes and leads the change in behaviour, (e.g. resuming grazing after resting), is important.
  • We want the hungry high producers to get up first from resting and start a grazing spell again and not the low producers.
  • Offering new feed regularly during the day by moving the fence will always get cows to resume grazing as well as feeding small amounts of feed more often.
  • Feeding concentrates will also get more nutrients into the rumen, but this is generally not economic in NZ.
  • Using additives like molasses to improve palatability will also increase intake.
  • Cows don't like musty, mouldy or dusty feed, and these will reduce intake.

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