livestock

• The total UK dairy herd size has been decreasing. However, the number of cows per individual dairy herds have been increasing
• Dairy production cycle


  1. Heifers start their cycle around 12 months of age, with bodyweight being the critical factor. This determines when puberty occurs

  2. Puberty- ideal is to get heifers cycling at 13 months and in calf by 15 months and calving at 24 months (about 2 years)

  3. Insemination at 14-15 months
• Holstein heifer


  • Weighs 600kg as an adult, should weigh 300kg at 12 months of age and put on 60kg before its 15 months old
• Annual reproductive cycle


  1. First ovulation after 1st insemination without oestrus

  2. Second ovulation at around 40 days (about 1 and a half months) after calving, 7-10 days (about 1 and a half weeks) after first ovulation. Not particularly fertile at this stage

  3. If you want to maintain a 365-calving pattern she needs to get in calf on the 3rd or 4th ovulation within 84 days (about 3 months)

  4. Pregnancy lasts 280 days (about 9 months)

  5. Cow calves
• Lactation


  Begins the day of the calf's birth. Peak lactation is between days 60-90 post calving after this time it declines continuously until dry off 305 days (about 10 months)
• Peak yield


  14d yield x 1.3
• Total lactation yield


  Peak yield x 200
• Voluntary waiting period (VWP)


  Interval during the postpartum period in which producers decide not to breed cows even if estrus occurs. It usually lasts about 50 days but may vary a lot from herd to herd according to the breeding strategy in place
• Seasonal systems


  • Reliant on grazed grass and conserved silage
  • Low input cost
  • Low output
  • Block calving in the spring (autumn also alternative)
  • Seasonal supply of milk
  • Breeds adapted to high forage diet- tend to be lower in yield
• Advantages of seasonal systems

  • Lower feed costs
  • Lower disease spread
  • Less complicated feeding
  • Reduced building cost- increased flexibility
  • Better fertility ?
  • Less slurry
• Disadvantages of seasonal systems

  • Holstein/ high producing cows ill suited
  • Increased land requirements- limits expansion
  • Cows use energy obtaining feed
  • Uneven production cycle and quality
  • Milk yields and fertility negatively correlated, health nutrition and welfare of animals need to be on top
  • Increased parasite problems (e.g. fluke and summer mastitis
• Year-round calving systems


  • Even spread of calving dates
  • Reliant on conserved forage and concentrate feeds – Total Mixed Ration (TMR)
  • High input/high output systems
  • High yielding breeds (Holstein genetics)
  • Some permanently housed (e.g. Trawsgoed)
  • More even milk supply throughout the year
  • More purchased concentrate
  • Shorter grazing season (if any)- more housing
  • More silage used
  • Usually higher milk yields
  • Higher milk price
• Disadvantages of year-round calving systems

  • Expensive to set up –capital
  • Vulnerable to increase in feed cost
• Milk price


  Determined by: contract type – compositional or liquid, Seasonality, Volume, Fat %, Protein %, Bactoscan- measurement of the number of bacteria present in milk
• Bactoscan


  Measurement of the number of bacteria present in milk (usually expressed as e.g. 20, meaning 20,000 bacteria/ml). High bacterial levels reduce the shelf life of milk and may affect the ability to produce good quality cheese. Legal requirements set by the EU for the milk to be suitable for human consumption, currently set at a maximum of 100,000 cfu/ml. Other targets set by the milk buyer with financial penalties for producers, this is used as an incentive to farmers to be as hyginic as possible
• Somatic cell count


  Main indicator of milk quality, majority of cells white blood cells in response to mastitis causing pathogen (cells/ml). SCC of 100,000 or less indicated an uninfected cow, where there is no significant losses due to subclinical mastitis. SCC of 200,000 would determine whether a cow in infected with mastitis. Greater than this value highly likely to be infected on at least ¼. SCC of 300,000 greater infected with significant pathogens
• Liquid Milk contracts


  Liquid milk not processed further (other than homogenization and pasteurization) – sold as liquid milk in bottles. Generally, only must meet minimum criteria in terms of quality (often legal minimum), however this varies with buyer and retailer
• Liquid milk requirements


  • Protein 2.8%
  • Fat 3.2%
  • Bacterial plate count 30C <100 000/ml (= 500 000/ml Bactoscan)
  • Somatic cell count No more than 400,000/ml
  • Freezing point depression No more than –0.520C
  • Antibiotics >0.004µg/ml: Penicillin, Undetectable: Others
• Lactation


  Key feature if mammals- ability yo produce milk. Milk glands produce milk. Milk production is an endocrine activity (hormone secretion) and exocrine activity (ducts for body secretions). Function: to provide nutrition for the new-Borns
• Milk composition


  • Fat
  • Protein
  • Lactose- sugar. Molecule of glucose and galactose. Main osmoregulator of milk volume. Cows aim to produce milk with lactose content of 4.8%
  • Minerals
  • Vitamins
  • Antibodies
  • Amino acids- casein and whey protein
  • Glucose- energy to the udder, convert glucose into Galactose and glycerol, produce lactose
  • Acetate and Butyrate- VFA from fermentation of carbohydrates in the rumen, energy to the udder, and used to create Triglycerides and Fatty acid chains
  • Fatty acid- play role in creating fats: triglycerides and fatty acid chains
• Milk fat depression


  Sudden drop in fat content. Lack of fiber in the diet or enough fiber but high levels of fat- fat interferes with fiber fermentation
• Physiology of Lactation


  1. Mammogenesis - development of the mammary gland. Lactogenesis - establishment of milk secretion post calving/lambing etc. Galactogenesis - continued production of milk by the mammary glands

  2. Progesterone promotes development of the alveoli and prevents the secretion of milk, supports the pregnancy

  3. Prolactin levels increase, promotes development of the secretory epithelium to promote milk secretion, increase when udder is empties

  4. Oxytosin stimulates milk letdown

  5. Growth hormone impacts milk production levels, where energy is directed in the body- more nutrence to the udder

  6. Feedback inhibitor of lactation- FIL present in milk, more milk in udder- more FIL, FIL inhibits milk production as well as internal physical pressure

  7. Alveoli cells are naturally lost over time – Involution

  8. Dry period - time between halting of lactation and the subsequent calving, repair of udder – new alveoli cells created
• Galactogenesis


  Continued production of milk by the mammary glands
• Progesterone


  • Promotes development of the alveoli
  • Prevents the secretion of milk
  • Supports the pregnancy
• Animal gives birth


  1. Prolactin levels increase

  2. Promotes development of the secretory epithelium to promote milk secretion

  3. Increase when udder is emptied
• Oxytocin


  Stimulates milk letdown
• Growth hormone


  • Impacts milk production levels
  • Where energy is directed in the body- more nutrient to the udder
• Feedback inhibitor of lactation (FIL)

  • Present in milk
  • More milk in udder- more FIL
  • FIL inhibits milk production as well as internal physical pressure
• Dry period


  1. Time between halting of lactation and the subsequent calving

  2. Repair of udder - new alveoli cells created

  3. Natural removal of pathogens
• Pathogen


  An organism causing disease to its host
• Disease


  Abnormal condition that adversely affects the structure or function of all an organism
• Pathogens


  • BSE - mad cow disease
  • Ringworm
  • Foot and mouth disease
  • Foot rot
  • Fasciolosis
• Foot and mouth disease has a genome size of 8000 and a reproduction time of 1 hour
• Main components of pathogens

  • DNA
  • Nucleus
  • RNA
  • Ribosomes
  • Mitochondria
  • Cell wall
  • Capsid protein
• Bacteria


  • Single celled
  • No nucleus or organelles (chloroplasts, mitochondria)
  • DNA and ribosomes for protein production
  • Some have attached characteristics (pilus, flagella)
  • Can be defined by their gram stain and by their shape and growth pattern

  
• Bacteria can have a positive role, e.g. in silage production, the gut of animals, and in the soil
• Protozoa


  • Single celled but more complex than bacteria
  • Larger and contain mitochondria
• Protozoal diseases


  • Coccidiosis
  • Abortion
  • Gastroenteritis
• Protozoa also inhibit rumen and ferment feed
• Fungi


  • May be a single cell (yeast) or multicellular organism (filamentous fungi)