Title: Calf Nutrition Issues and Factors Affecting Rumen Development Dr. Howard Tyler Department of Animal Science Iowa State University
1Calf Nutrition Issues and Factors Affecting Rumen
Development Dr. Howard TylerDepartment of
Animal ScienceIowa State University
2Meeting The Nutrient Requirements of the Calf
- A nutritionists nightmare
- Entire pre-weaning period is transition period
from non-ruminant to ruminant - proportions of nutrients provided by liquid vs.
solid feeds in constant flux - physical capacity of rumen increases
- potential for dry matter intake also increases
- fermentative capacity of rumen increases
- absorptive capacity of rumen increases
- therefore, digestibility of solid feeds also
changes as rumen develops
3Energy Requirements
- Approximately 20 kcal/pound of body weight in a
thermoneutral environment for maintenance - Eighty pound calf requires ?1500 kcal maintenance
and 850 kcal for 0.5 lb of gain (2350 kcal/day
total) - Requirements increase 1 for every degree below
500 F - High surface areabody mass ratio
- Require 450 kcal more at 200 F (2800 kcal/day
total) - Difference between ruminating calves and
non-ruminating calves - Difference between small and large calves
4Body Size and Growth Rate Affects Protein
Requirements
- The size of the calf affects the protein
requirements at any given level of intake - For 95 lb calf receiving 10 ounces of milk
replacer twice daily, a 2020 milk replacer meets
the protein needs - An 85 lb calf receiving the same amount of milk
replacer needs 22.5 protein, and a 75 lb calf
needs 25 protein - Less energy needed from maintenance in lighter
calves, so more energy available for growth - Therefore, more protein required to support lean
growth - Required proteinenergy ratio needed changes with
rate of gain targeted and size of animal being fed
5Factors Affecting Protein Requirements
- Rate of gain determines amount of protein
required - If facilities, genetics, and calf
source/management permit rapid gain, then high
levels of protein and energy required in diet - If facilities, genetics or calf source/management
LIMIT rate of gain, then protein and energy must
be reduced accordingly - The size of the animal affects the protein
requirements at any given level of intake - Less energy needed from maintenance in lighter
animals, so more energy available for growth - Therefore, more protein required to support lean
growth - Frequency of feeding affects digestive efficiency
- Natural suckling frequency allows greater intake
than most hand-feeding systems can achieve - Required proteinenergy ratio changes accordingly
6Imbalanced ProteinEnergy Ratios
- If energy diverted to immune function (poor
facilities), then it is NOT available for growth - Excess protein must be de-aminated and ammonia
detoxified and excreted - Energy required (3 ATP per molecule of urea) and
therefore even LESS energy available for growth
and immunity - Overfeeding protein (in this case by underfeeding
energy) impairs growth and may impair immunity
7Is Mortality Rate an Issue? (Summary)
- Under excellent management conditions, there is
no evidence that calves fed higher levels of
protein (appropriate for maximal growth rates)
are at more risk or less risk for dying - Under marginal conditions, calves fed higher
levels of protein may be at higher risk - Under highly challenging conditions, calves fed
higher protein levels are at higher risk of dying
than calves fed conventionally - This begs the question do calves on
- a higher plan of nutrition have a stronger
- immune system or a weaker immune system?
8Does Higher Plane of Nutrition Higher
Functioning Immune System?
9Does Higher Plane of Nutrition Higher
Functioning Immune System?
10Does Higher Plane of Nutrition Higher
Functioning Immune System?
11Does Higher Plane of Nutrition Higher
Functioning Immune System?
12Challenges with Liquid Feeding Strategies
- High energy intake from liquid feed delays
initiation of starter intake and suppresses
appetite for starter - high fat inclusions during cold weather
- higher solids in the same volume
- of milk replacer
- higher volume intakes
- Must balance accelerated growth with accelerated
rumen development
13Establish Microbial Populations
- After birth aerobic bacteria colonize
- Anaerobic bacteria soon dominate
- cellulolytic and methanogenic first
- lactate-fermenting exceed adult values then
decline - protozoa introduction requires contact with
mature ruminants - Influenced by access to solid feed and the
composition of the ration
14Water
- Water availability may limit starter intake
- free water necessary for development of rumen
fermentative capacity - water in milk replacer bypasses rumen
15The Rumen at Birth
- At birth, the rumen and reticulum are under
developed, sterile, and non-functional - Milk bypasses the reticulorumen by the esophageal
groove - The reticulorumen comprises less than 1/3 of the
entire stomach volume
16The Rumen at Weaning
- The rumen is the primary compartment (over ½ of
stomach volume) - Size, metabolic activity, and blood flow have
increased markedly - The rumen modifies both energy and protein prior
to digestion by the calf
17Absorptive Ability of Rumen Tissue
- The rumen wall consists of two distinct layers
- musculature
- absorptive epithelium (mucosa)
- The mucosa is responsible for absorbing VFA
- Muscle is develops in response to material in the
rumen - Development of the mucosa depends on the
production of VFA - Roughage does NOT stimulate mucosal growth
18Rumens of 4-Week-Old Calves
Milk and Hay
Milk, Grain, and Hay
19What is the Right Balance?
- Concentrates
- VFA production
- butyrate
- High in energy
- fermentable carbohydrates
- Palatable
- Forages
- Low in energy
- structural carbohydrates
- Ruminal abrasion value (RAV)
- Bulk
- Rumination
20Starter Without Hay
Textured
Commercial textured starter
CP - 23.58 ADF - 6.39
Ground
CP - 25.44 ADF - 6.44
21Importance of Particle Size
- Particle size of the diet influences
- Palatability
- Speed of digestion
- Rate of acid production
- Rumen retention time for digesta
- Rumen pH via saliva production
- Integrity of rumen papillae (RAV)
22Starter With Grass Hay
Coarse 7.5 Hay
Hay of consistent particle size
CP - 23.08 ADF - 6.47
Coarse 15 Hay
Hay of consistent particle size
CP - 22.60 ADF - 7.43
23Calf Starter with 7.5 Grass Hay
- Increased body weight
- Increased feed efficiency
- Alters rumen VFA production
- increased acetatepropionate
- Creates a more stable rumen environment
- Decreased starter costs
- significantly improved feeding profitability
- 4 lbs chopped hay per 50 lb bag of starter
24Changes in Nutrients Utilized by Calves After
Rumen Development
- VFA are produced in the rumen and become an
important source of energy - Blood glucose declines
- Ruminal bacteria increase in population and
become a primary source of protein - 50 protein
- 80 digestible
- High biological value
25Weaning Strategies
- Level of calf starter intake correlates with
maturity of rumen fermentative function as well
as physical development of rumen - Weaning should be intake-based
- Weaning reduces labor costs by 50 and costs of
gain by 3 to 5-fold - earlier weaning of healthy calves is most
profitable
26Can A Ruminant Survive Without A Rumen???
- Rumenectomies (early removal of the rumen) or
prolonged milk feeding used to answer this
question - Young ruminants will survive for a time without
rumen fermentation - Animal viability decreases and sudden death
occurs between 6 and 8 months of age - Can be reversed almost immediately by providing
food to the rumen!!! - Ruminant animals hard-wired metabolically to
function as ruminants - Must utilize the end-products of microbial
fermentation
27On raising calves
- The first four weeks of its life the calf must
receive the whole of its mothers milk, because
in this period the nutrition contained in the
milk in so small volume can be replaced by no
other equally nutritious and as easily digestible
means of food. - After four weeks the milk may be replaced by that
means of fodder which nutritious substance next
to it in equal weight of dry volume, in the
greatest possible amount.
USDA, 1847