BRAHMAN NEWS JUNE 2015 ISSUE #187 PAGE 36
By Alex Ashwood
Diseases of the newborn calf can cause unacceptable wastage and calf losses reducing weaning rates and farm profit.
Basic information on calf immunity and keeping in touch with new information and developments can assist in minimising disease and improve the survival of calves from birth to weaning.
Survival of calves from birth to 4-6 months and the avoidance of death and wastage due to scours and respiratory infections depends on newborn calves obtaining passive immunity then developing natural immunity.
Calves are born with a total lack of immunity to infectious diseases. Disease fighting immunoglobulins (1g) are not transferred across the placenta from the cow to the developing calf foetus. Whilst active immunity can be obtained from vaccination programs and antibodies produced to fight infection, the initial protection in newborn calves is dependent on the transfer of immunoglobulins (antibodies) from the cow to the calf.
“Passing antibodies from the cow (via colostrum) provides passive immunity”
The colostrum (first milk) produced by the cow plays a fundamental and critical role in enabling the calf to establish a defence mechanism against disease.
The calf’s immune system does not function effectively until the calf is 4-6 months old. If the calf fails to suckle or for some reason does not receive an adequate amount of colostrum, it must rely on an immature immune system which provides inadequate protection from disease.
Colostrum deprived calves synthesise immunoglobulin from birth but it takes considerably longer (3-4 months) to reach similar immunoglobulin serum levels found in calves fed adequate levels of colostrum.
If the disease challenge is overwhelming and the calf hasn’t ingested sufficient amounts of antibodies via the colostrum the calf will succumb to the disease.
“Colostrum the primary source for immediate passive immunity and protection”
Calves that do not ingest sufficient amounts of high quality colostrum soon after birth are three times more likely to get sick and five times more likely to die compared to calves that receive sufficient levels of immunoglobulins (lg).
Colostrum provides a preformed source of immunoglobulins which is actively absorbed across the small intestine to provide protection from infection. Part of the antibodies remain in the gut where they can neutralise pathogenic bacteria and help prevent diarrhoea (scours) in the first 3-4 days after birth. For protection from infection the colostrum must be absorbed shortly after birth (Table 1).
Various factors affect the intake and absorption of sufficient antibodies. The efficiency of immunoglobulin intake and absorption is decreased when the antibody level in the colostrum is low. Factors that affect the level of antibody intake and subsequently the level of passive immunity are:
Whilst factors affecting colostrum quality and the actual absorption of antibodies is complex, there is, however, sufficient knowledge to prevent hypoimmunoglobulinmia (ie low blood levels of immunoglobulins).
Cows colostrum contains about 22 percent total solids compared to 12 percent in normal milk. Different breeds have different levels of total solids. Beef cows tend to produce less milk but with a more concentrated colostrum. Colostrum is also a rich source of protein (casein), fat, sugars and vitamins (particularly A & E) which are essential to the nutrition of the newborn calf.
Table 1: Effect of time feeding on total immunoglobulin (lg) absorption of newborn calf.
|Time of Feeding (hrs after birth)||Plasma Concentration (mg/ml) (hrs after feeding)||Absorption (%)|
“A number of factors influence the total amount of antibodies in colostrum”
It cannot be assumed that the immunoglobulin concentration in colostrum is the same in all cows and heifers. Mature cows produce more colostrum of higher quality than heifers and aged cows and there can be considerable differences between individual animals.
The antibody status of calves increases with the amount fed with suitable immunoglobulin serum levels attained when calves are fed 2 litres in the first 6 hours and a further 3-4 litres in the next 6-8 hours. Approximately 100 gms of immunoglobulins are in 2 litres of colostrum.
“Blood serum levels of immunoglobulins increase linearly with the amount of immunoglobulin”
Better quality colostrum (ie colostral with high concentrations of immunoglobulins) improves the antibody and passive immunity status of the calf. Colostrum low in antibodies requires higher levels of intake. However calves fed higher levels of low quality colostrum have less antibodies than calves fed lesser amounts of high quality colostrum.
Studies (Ohio State University) showed that cows on a high plane of nutrition provided more colostrum with more antibodies than underfed cows.
Researchers in Wyoming found a 10 percent increased incidence of calf deaths and a further 19 percent deaths from scours in calves from dams on low levels of feed in the last trimester of gestation.
Further studies (Colorado State University) examined the level of disease protection provided to calves from heifers at various body condition scores (Table 2). The researchers found that the heifers in better condition produced more colostrum with a higher immunoglobulin content.
Mothering has a major impact on the intake of colostrum. If the calf does not suck within the first 24 hours post calving it will be hypoimmunoglobimemic.
Cows with well-structured udders and teats have been shown to produce better grown calves than cows with poor udder and teat conformation.
Figures 1 and 2 provide examples of good udders with good teat shape and placement. The udder is well balanced with good attachments supporting well placed properly sized and shaped teats with good texture. Bottle teats, long teats and poorly portioned teats cause major problems to the newborn calf (Figure 3 and 4). Udder edema (Figure 5) which is generally more prevalent in heifers, can seriously limit antibody intake due to reduced suckling by the calf.
The poorer mothering ability of heifers compared to aged cows is often compensated by the better udder and teat conformation of heifers.
“Some newborn calves lack the instinctive ability to suck”
Calves that have poor sucking behaviour is a condition called “dummy calf syndrome” or “poor sucking reflex” (PSR). This condition is different to neurological disorders at calving (eg Akabane disease or Pestivirus).
Poor sucking reflex accounts for a high proportion of sucking problems and if not attended to can cause high mortality rates of calves. PSR calves are
Table 2: Effect of body condition score (BCS) at calving on the interval from calving to standing and level of immunoglobulin(lg) production.
|Body Condition Score|
|3 (Very Thin)||4 (Thin)||5 (Average)||6 (Good)|
|Interval from calving to standing (mins)||59.9||63.6||43.3||35.0|
|Total immunoglobulin (Ig)*||2192||2351||2445||2653|
(*concentration mg/dl in serum 24 hours after birth)
Note: The higher immunoglobulin concentrations in the calves was attributed to a combination of higher levels of antibodies, the dams better condition score and increased activity of the calf.
hypoimmunuglobinemic and like all calves with insufficient intake of colostrum are prone to infection and disease.
“Failed passive immunity is due to the lack of antibody intake and absorption”
PSR has a genetic predisposition, suggesting the influence of the dam, sire or both. Where there is a higher than normal occurrence of PSR it is probable that the sire of the calf or dam are the common factors involved.
“Stress reduces the efficiency of antibody absorption”
Stress due to unfavourable environments (climate and/or surroundings) can impair bonding between the cow and calf and reduce colostrum intake. Extremes in temperature also lessen the efficiency of immunoglobulin absorption.
Heifers are prone to stress particularly if placed in strange surroundings, have disrupted calvings and prolonged, difficult calving which leads to weak calves and poorer “mothering” ability.
Lengthy, difficult calvings have a significant effect on the cow-calf relationship, particularly the vigour of the calf and the level of immunoglobulin intake (Table 3).
Assisted calves often result in less vigorous calves, the cow is frequently exhausted and with heifers the calf may be abandoned after stressful calvings. Generally if the heifer fails to lick the calf shortly after birth, “mothering” is dramatically reduced.
“Reducing calving difficulties increases colostrum intake and passive immunity”
Calves experiencing prolonged and/or difficult calvings often do not receive sufficient antibodies due to low colostrum intake, lower quality colostrum and reduced immunoglobulin absorption efficiency. Very often the calves suffer from respiratory and metabolic acidosis which reduces the activity of the calf.
Where necessary, early (not premature) calving intervention (obstetrical assistance) results in more vigorous calves, eager to stand and suck and mothers with a higher “mothering” drive than lengthy difficult calvings.
“Calving difficulties decrease the transfer and absorption of antibodies”
With the increased emphasis on frame score and larger cattle, greater attention needs to be given to sires that do not cause prolonged and difficult calvings.
Calves may require an alternative source of colostrum due to a number of reasons:
Alternative sources of colostrum include fresh and frozen colostrum and commercially available products. When sourcing colostrum from a dairy farm it is essential that no new diseases (eg Johne’s disease) are not introduced to the herd.
The quality of colostrum can be estimated with the use of a hydrometer. A specific gravity of less than 1.05 is associated with low immunoglobulin content.
Colostrum can be delivered by bottle suckling or force feeding using a oesophageal feeder (ie stomach tubing). Care must be taken with stomach tubing to ensure that colostrum enters the rumen or fore stomach and not the windpipe and lungs.
“Care needs to be taken when thawing out frozen colostrum”
Rapid defrosting and stirring denatures the protein antibodies. The two methods recommended for thawing colostrum are:-
Note: Both procedures take about 40 minutes and at the completion of thawing the colostrum should be approximately 104oF (40oC).
Table 3: Effect of calving difficulty on serum concentration level, calf activity and mothering.
|Calving Difficulty Score|
|Calf Activity (minutes from calving to standing)||39.5||50.9||84.3|
|Immunoglobulin (IgG) intake (mg/dl)||2401||2191||1918.5|
Note: 1 = unassisted, 2 = assisted after one hour of labour and easy pull, 3 = assisted after 1 hour of labour and difficult pull.
Passive immunity to prevent infection and disease is gained by the post natal calf through colostral antibodies. The colostrum contains immunoglobulins that are absorbed from the intestine into the bloodstream by the newborn calf providing partial immunity.
If the newborn calf is seriously challenged by infection and/or does not receive sufficient high quality colostrum in the first 18-24 hours after birth the calf is at risk of serious infections and disease (eg scours, septic arthritis, pneumonia).
Passive immunity provides early protection (4-6 weeks) whilst the calf is developing natural immunity. Immunity is not gained until 4-6 months after birth and subject to potential of disease challenges the calf may need vaccination for a specific disease (eg blackleg). The necessity for an ongoing strategic vaccine program will depend on the threat/risk of a specific disease to the herd.
Factors that enhance the intake and absorption of sufficient levels of immunoglobulins are:
Financial and genetic losses due to disease and death of newborn calves is a concern to beef producers. This article outlines some of the factors that impact on passive immunity, colostrum quality and the transfer of sufficient levels of antibodies (immunoglobins) via the colostrum from the dam to the calf.
“Early protection from disease comes from passive immunity provided by colostral immunoglobulins”
|Checklist When Feeding Colostrum|
|Other Management Tasks||
“Desirable and Undesirable Udders” - ABBA Brahman News, March 2008
“Poor Suckling Reflex” - ABBA Brahman News, September 2004
“Anatomy and Endocronology” - ABBA Brahman News, December 2011
“Reproduction - Herd Health” - ABBA Brahman News, September 2011
“Calving Ease and Dystocia” - ABBA Brahman News, March 2010
“Immune Systems and Vaccination” - ABBA Brahman News, December 2014