Cattle Nutrition Flashcards
(40 cards)
What is the ratio of Primary: Secondary rumen contraction?
What is each one followed by?
2 Primary: 1 secondary
Followed by regurgitation
How much DMI in % does a lactating cow need to eat per day?
4% (30-50 litres per day)
What does microbial fermentation of carbohydrates produce?
Volatile Fatty Acids (VFAs)
Carbon dioxide
Methane
How are VFAs produced and used?
What happens to proprionate?
Produced by microbial fermentation of carbohydrates
Absorbed across rumen wall
Enter Krebbs cycle to produce energy
Proprionate goes into glucose synthesis to produce milk
What is the target BCS loss for early lactation?
0.5-1 BCS
1 BCS = 50kg
How much energy is required (MJ) for maintenance?
How much energy is required per litre of milk?
65-70 MJ
5 MJ/litre milk
How is protein degraded in the rumen?
It is fermented in the rumen
Broken down into ammonia
Turned into microbial protein (by microbes)
Digested in abomasum and SI
What happens if rumen microbes don’t receive enough energy for protein synthesis?
Ammonia is absorbed across the rumen wall
High urea in the blood
What is the DMI (kg) in the dry period?
What is the danger level?
12-14kg
< 11kg/cow
Which type of silage has the highest ME?
What about protein, starch and fibre content?
Maize silage
Low protein, high starch (FME), poor long fibre source (short + pulverised)
Describe these feeding systems for lactating cows: Traditional TMR "Hybrid" Buffer feeding
Traditional: - Silage at barrier and cake in parlour - Grazing in summer and cake in parlour Total Mixed Ration: - All food at barrier, 24 hours a day, ad lib "Hybrid": - Partial mixed ration at barrier - And cake in parlour Buffer feeding: - TMR supplement to grazing in the summer
What is the disadvantage of a “Hybrid” feeding system for lactating cows?
Risk of SUBSTITUTION
Cow eats more concentrate in parlour, will eat less forage in barrier
Reduced long fibre intake
Risk of SARA (reduces DMI)
What is BHB (Beta-hydroxybutyrate) an indicator of?
Negative energy balance
Subclinical ketosis
How many days is the calving index?
How many days is the dry period and the lactation period?
370-400 days
60 days dry period
305-340 days lactation period
What is the transition period?
3 weeks before to 3 weeks after calving
What is the periparturient period?
Period immediately before and immediately after calving
What are the 3 requirements for cows towards the end of the dry period and the start of lactation?
What is the main problem with this?
- Foetal growth
- Mammary development
- Milk production
DMI is reduced! Cows are entering a period of NEB
What is the main energy source at the start of lactation?
How is this produced?
Glucose Ruminal fermentation Produces VFAs: Propionic acid (form of proprionate) Absorbed across rumen wall Enters Krebs cycle for gluconeogenesis
What is the main energy reserve used in NEB?
Adipose tissue (NEFAs released)
What is “Fatty liver”
Reduced hepatic function
Due to excess NEFAs converted into triglycerides and stored as fat droplets
What are 3 problems with obesity in dairy cows?
- Accumulation of fat in the liver reducing hepatic function, “fatty liver”
- Type 2 diabetes, decreased response to insulin
- Proinflammatory cytokines from adipose tissue cause inflammation in liver
Which type of fat distribution do Holsteins tend to have?
Visceral fat “hidden”
When should you check the BCS in dry cows?
At drying off
Halfway through dry period
At calving
Early lactation
What are the risks of overfeeding during the dry period?
- Major increase in visceral fat (little increase in CS)
- Decreased immune function
- Risk factor for metabolic syndrome
