Farm Ireland
Independent.ie

Friday 24 March 2017

Born and bred for a healthy future

To ensure calves are in top condition, minimise exposure to disease and defend against it

Dr Mark McGee and Dr Bernadette Earley

Management and environment

To ensure a healthy calf, the aim is to minimise the calf's exposure to disease, and maximise its defence against disease. In minimising a calf's exposure to disease, providing a clean, disease-free environment is fundamental. This involves:



  • Thorough cleaning and disinfection, before and during the calving season, of all areas used by calves.
  • Providing a clean, straw-bedded lying area with no draughts and good ventilation.
  • Accommodating cows and calves in batches based on order of calving so that young calves are never mixed with or accommodated in areas used by older calves.
  • Avoiding introduction of disease from sources such as purchased calves. Isolate all purchased animals from young home-bred calves.


In maximising a calf's defence against disease, control measures include:



  • Adequate nutrition of the pregnant cow, including feeding a suitable mineral supplement prior to calving.
  • Vaccination of cows for control of any organism(s) known to be responsible for infection on the farm in calves. These include E.coli, rotavirus and coronavirus. In this respect, vaccination alone is not a replacement for good management, good hygiene or good biosecurity. A veterinary practitioner should always be consulted with regard to specific health problems.
  • Disinfecting the calf's navel immediately after birth.
  • Ensuring that each calf receives sufficient colostrum (first milk) immediately after calving. Adequate intake of quality colostrum is one of the most important factors in ensuring survival and health of the calf. Additionally, there is no point in vaccinating the cow against specific calf diseases unless the calf consumes the colostrum produced.


Colostrum and calf health

The calf is born without any resistance to disease and is completely dependent on immunoglobulins (antibodies) in colostrum as a mechanism to fight disease in early life. Prevention of disease begins with the effective transfer of immunity to the new-born calf through adequate intake of colostrum -- this is known as passive or humoral immunity. The immunoglobulins obtained from colostrum must be consumed within the first few hours of life in order to provide the calf with a disease defence mechanism until it builds up its own resistance through its own active immune system. A calf that does not receive adequate immunoglobulins at birth is very susceptible to pathogens such as E.coli, Salmonella, Rotavirus and Coronavirus. Research at Teagasc, Grange has clearly shown that dairy calves with low levels of immunoglobulins had the highest incidence of diarrhoea, respiratory disease and mortality.

The main factors influencing immunoglobulin levels (concentration) in the calf serum are: (1) time of feeding/suckling, (2) volume of ingested colostrum and (3) immunoglobulin level in colostrum. Consequently, with regard to colostrum feeding, there are a number of main points which must be noted.

1. Time of feeding




  • The immunoglobulins in colostrum must get into the calf's blood via absorption from the small intestine.
  • The ability of the calf to absorb these immunoglobulins decreases linearly after birth and generally stops after 24 hours.


This means that the earlier a calf is fed/suckles after birth, the greater the level of immunoglobulin absorption. Ideally, the calf should ingest colostrum within one hour of birth. There are also advantages in continual colostrum ingestion after the first day as the immunoglobulins in colostrum also act locally in the gut and help fight against septicaemia.

2. Colostrum yield and immunoglobulin level, and calf immunity

Our research at Grange on the spring-calving suckler herds has shown that:



  • The immunoglobulin level (quality) is similar between quarters (teats) of the udder and is also similar within a quarter, that is, as the quarter is milked/suckled out for the first time.
  • The immunoglobulin level of second-milking colostrum is only half that of first-milking colostrum (Tables 1 and 3). This highlights the importance of the colostrum present in the udder at birth, which should be consumed first before returning to a quarter previously milked/suckled.
  • Calves from cows that are severely feed restricted before calving, such as feeding a straw diet, have significantly lower immunoglobulin levels than calves from cows adequately fed before calving (Table 1).
  • Calves from heifers have a significantly lower immunity than calves from mature cows. This is mainly because of a lower colostrum yield (Table 1).
  • There are large differences in immunoglobulin levels in calves from different cow breed types. Calves from the dairy herd have lower immunoglobulin levels than calves from the suckler herd (Table 2). All else being equal, this is primarily due to the much lower concentration of immunoglobulins in colostrum of dairy cows compared to suckler cows.


Calves from beef breed cows generally have lower immunoglobulin levels than calves from beef × Friesian cows (Table 3). The main reason for this is that colostrum yield of beef cows is lower than that of beef × Friesian cows (Table 3). Calves from suckler cow breed types with lower milk yield potential generally have lower immunoglobulin levels than calves from suckler cow breed types with higher milk yield potential (Tables 4 and 5). Again, this largely relates to differences in colostrum yield.

3. Volume of colostrum to feed

Our results from the suckler herd showed that feeding a first-milking colostrum volume equivalent to 5pc of birth weight (eg, 2l for a 40kg calf, 2.5l for a 50kg calf) within one hour of birth resulted in relatively good immunity levels. However, it is very important that the calf then suckles within a few hours.

Conclusion

Studies with suckler herds at Grange showed that when attention was given to ensuring adequate colostrum intake, high levels of immunoglobulins were present in the calf serum.

However, calves from heifers and from cows severely feed restricted in late pregnancy had lower levels of immunoglobulins than adequately fed mature cows.

Calves from suckler cow breed types with lower milk yield potential have lower levels of immunoglobulins than calves from breed types with higher milk yield potential.

Irish Independent