Dairy Cattle Selection and Life Cycle

1
Dairy Cattle Selection and Life Cycle

• Chapter 27

2
US Dairy Industry History

• Jamestown Colony 1611
• 21st Century
• 90 of the milk produced by one breed
• Holstein
• Dairy size is increasing dramatically

3
Life Cycle Calf

• 1 day of age weaned
• Feed colostrum
• Sell males?
• Dehorn
• Castrate
• Weaned from milk at 1 month of age
• Dry feed

4
(No Transcript)
5
Lactation
Dry Period
6
Life Cycle Bulls

• Pre-selected via planned mating
• AI/ Bull Studs
• Very few bull calves selected
• Feedlot performance NOT tested in the USdont
  care about it.

7
Improving Milk Production

• Number of dairy cows has decreased
• Amount of milk produced has increased
• P. 485 Figure 27.2

8
Dairy Cow Selection

• Productive life of a diary cow is short
• Cows are culled due to
• Reproductive failure, low milk yields, udder
  breakdown, foot and leg weakness, and mastitis
• Select heifers with good milking genetics
• Basis of evaluating dairy

9
Dairy Cow Selection

• National Cooperative Herd Improvement Program
  (NCDHIP)
• Referred to as Dairy Herd Improvement (DHI)
  program
• National, industry-wide production-testing and
  record keeping program
• Approximately ½ of all U.S. dairy cows are
  enrolled
• 4.5 million cows
• Facilitates the development of a national
  database that is used for genetic selection

10
(No Transcript)
11
Breeding Dairy Cattle

• Time of breeding is important
• Cattle are evaluated per day
• In estrus cows show
• Cattle are artificially inseminated
• DHI technicians or producers
• Use semen of genetically proven sires
• Even if semen is a little more expensive, worth
  the money because of the increased milk
  production

12
Breeding Dairy Cattle

• Heritability
• Cystic ovaries, ketosis, mastitis, milk fever (5
  10)
• Fat percentage, protein, solids-not-fat (50)
• Yearly milk, protein, solids-not-fat, fat yields
  (25 30)

P. 489 Table 27.5
13
Breeding Dairy Cattle

• Genetic Correlations
• Milk yields during first lactation (0.70 0.90)
• Fat, solids-not-fat, protein yield, lifetime milk
  yields, length of productive life

14
Breeding Dairy Cattle

• Inherited Abnormalities
• There are no more abnormalities in dairy cattle
• More closely observed
• Infrequent
• Most are due to recessive genes
• Do not keep for breeding stock if there are known
  inherited abnormalities

15
Breeding Dairy Cattle

• Why has there been such rapid improvement in milk
  production?

16
Breeding Dairy Cattle

• What traits does a cow need to remain productive
  for several years?

17
Breeding Dairy Cattle

• Most dairy cattle are purebred
• Crossbreeding has not successfully improved milk
  production

18
Breeding Dairy Cattle

• Bull Selection
• Evaluated for their ability to transmit the trait
  of high-level milk production
• Ancestry and daughters
• Sire genetic evaluation
• Compares daughters of a sire with herdmates
• Predicted transmitting ability (PTA)
• Based on their superiority or inferiority of his
  daughters to their herdmates
• USDA publishes PTAs

19
Sire Selection

• Use of best linear unbiased prediction (BLUP)
• Estimates PTA among sires
• Accounts for genetic competition among bulls with
  a herd, genetic progress of the breed over
  generations, pedigree information available on
  young bulls, differing number of herdmates
  sires, differential culling of daughters among
  sires
• Direct comparison for bulls that have daughters
  in the same herd
• Indirect comparisons made for bulls with
  daughters in two or more herds

20
Chapter 27 Objectives

• Understand how milk production and cow numbers
  have changed over the years.
• What are the reasons that dairy cows are
  typically culled?
• What are factors that may affect the productive
  life of a dairy cow?
• Why are most dairy cattle purebred?
• What types of things should you evaluate dairy
  bulls for?