In recent years, adjustments to the production costs in the dairy industry becomes crucial in light of current circumstances. There has been a continuous reduction in profit margins and increasing instability in this industry. Each stage in the production process requires maximum efficiency from both professional and economic points of view. The calf rearing stage is an integral part of the dairy business, and takes large part in determining the future quality of a dairy herd.
A simple analysis of growth rates of replacement heifers shows that the animal must double its weight within a specified period and achieve growth (in terms of shoulder’s height) of approximately 25% of a heifer’s total growth from birth to first calving. The positive correlation between shoulders’ height, skeletal growth, and milk production was already demonstrated (Shamay et al, 2005, Moalem et al, 2010) and should be taken into account.
The birth to weaning phase is crucial, because at that stage many important processes that are involved in the productive capacity of the replacement heifer occurs. For example, during this stage the calf’s digestive system is functioning as monogastric, and then it undergoes a transition to ruminant digestive tract. (It is important to emphasize that the process begins during this period but is completed after weaning)
It should be indicated that calves are very sensitive to diseases, and up to 90% of culled replacement heifers occurs at the first 4 weeks of life. In Israel, the average mortality rate from calving up to the first 24 hours of life is about 8% and until weaning another 4% died.
In summary, this stage of growth has three main objectives; 1- Low rate of morbidity and mortality; 2- Early rumen development’ and 3- A steady growth rate. Hence, the producer must seriously consider implementing proper practices to achieve efficiently these three objectives.
The objective of this article is to review the factors that directly influence the calf growth until weaning. It is important to clarify that the present “checklist” was generated for replacement heifers reared in intensive systems, in which the calves are housed, weaned at approximately 60 days, and later on, each group (according to their age) is fed with TMR according to professional recommendations.
The main goal of raising replacement heifers is to get the heifers to first calving, where they will be able to fully fulfill their genetic potential at low economic and environmental expenses, at proper calving weight, height, and body condition score.
PRE CALVING STAGE
It should be taken into account that the nutritional requirements of the dam (energy and protein) during the pre-calving stage will be increased. On the other hand, dry matter intake of the dam during the last 21 days prior to delivery, may be decreased by 30%.
In most of the cows, the energy balance will be negative at the end of gestation and during the first weeks after delivery, which is directly connected to possible postpartum diseases, and the interval from calving until first insemination.
In reference to nutrition, the daily expected consumption during the dry period will be on average 15-16 Mcal and 1200 g of metabolizable protein. The diet density will be 1.55 Mcal/ kg DM and 14- 15% crude protein. It should also be noted that the pre-calving diet should provide a balanced vitamin nutrition (A: 100,000 to 125,000 IU per cow per day, D: 35,000 to 40,000 IU per cow/day and vitamin E: 1200 to 2000 IU cow/day).
Other important factors:
- Separate the calving cows from the rest of the herd
- Create a comfortable calving area that allows the management of the cow in case of difficulties in calving. (One person’s job is to move cows from the close up pen to individual pens and assist with birth. Calves are pulled only when necessary according to a working protocol)
- Ensure free access to food (feeders 65-75 cm/cow)
- Ensure free access to water (20 cm of water trough/head)
- Ensure protection from winds and rain
- Provide shade and ventilation for hot periods
- Use clean bedding that also allows for easy replacement and disinfection (if possible with rubber carpet)
- If there are individual calving pens, their size should be approximately 4X4 meters. One hutch should be calculated for every 20 cows in the herd.
- Provide a well-lit environment (good artificial lighting is necessary for deliveries during hours without natural light).
Colostrum management should take into account three important factors:
- Hand sanitation/cleaning prior to milking
- Sanitation/cleaning the container in which the colostrum will be collected
- The udder must be prepared with the same protocol used prior to and throughout the milking duration
- It is recommended that the colostrum collection does not last more than 15 minutes.
- After collection or prior to storage, the quality of the colostrum should be measured. To do this, select an instrument for measuring the quality of colostrum, for example colostrometer or refractometer. Take into account the optimal conditions and limitations that each instrument presents.
- Colostrum pasteurization is recommended to avoid risk of disease contamination
- Store the colostrum in the refrigerator at 4 oC for up to 4 days or in the freezer -19° 18°- for longer periods
- It is recommended to divide the collected colostrum into rations of 1 or 2 liters according to farm management. It is important to record the quality on the container/bag in which it will be stored.
- Prior to colostrum collection, check the cleaning and disinfection of the tools that will be used
- The necessary colostrum rations and tools must be prepared in advance according to the calving schedule
- Utensils for defrosting and heating colostrum rations up to a temperature of between 38-40 oC will be necessary. Avoid heating to higher temperatures, since it can generates protein denaturation and causes a damage to immunoglobulins
- Mixing colostrum from different sources is not recommended (unless your colostrum is pasteurized). There is a high potential risk of disease spread Mycobacterium avian Paratuberculosis - (the organism that cause Johne’s disease), Salmonella, Mycoplasma, Listeria, E. coli and many others
- It is recommended to provide 4 liters of good quality colostrum during the calf's first hour of life.
- It is recommended to supply another 2 liters by up to 6 hours of after birth
- The use of a gastroesophageal tube should be evaluated, in cases where the calf does not consume enough colostrum.
- Over the next three days, 3 liters of transitional milk/colostrum (pasteurized) from second or third milking will be supplied twice a day.
Immediately after birth, the umbilical cord must be cleaned and disinfected
- Cleaning and disinfection is done by immersing the umbilical cord in a 7% iodine solution (iodine tincture) or ethanol solution
- Immerse the entire cord to help it dry quickly
- The calving area where the calf remains after calving should be filled with clean bedding material to help keep the umbilical area clean and disinfected. This will reduce the risk of infection and provides hot and cold insulation.
- Use clean and fresh material for each calf
- All utensils, after being used, must be stored in dry and clean places
- Repeat the iodine immersion operation for several days, until you make sure that the area is healed and dry (without fluids in the cord). Consider the use of paste or spray repellents to control worms
- Feel/palpate the area to make sure there is no inflammation or pain
Poor sanitation and mismanagement of the calving area/pen cannot replace the umbilical cord dipping for disinfection. Both measures must be carried out.
Calves should be fed at least twice a day (during the first three weeks), at the same time each day, preferably in the early morning and a second time preferably in the afternoon or evening hours, regardless of times scheduled of the milk or the replacement milk supply. In the case of supplying a third time, it is recommended to do so at night.
The third daytime supply may be necessary to provide nutrients and energy during cold weather, or for small or weak calves.
- It should be noted that the quantities of milk or milk replacer can vary considerably, ranging from 420 to 800 g DM/day, depending on whether the farmer's decision is to use nutritional management systems with accelerated or standard growth rates (this topic will not be discussed in this article because it requires, due to its importance, special discussion beyond the scope of this piece)
- Marketable milk
- Transition milk (milk produced within the first four days after parturition)
- Disposable or non-marketable milk (pasteurized only)
Milk consumption is calculated based on approximately 10% of the animal's live weight. Animal of 40 Kg should consume approximately 4 liters of milk/day.
The following factors should be taken into consideration:
- Have a biosecurity program: planning your disease prevention and treatment program.
- Cleaning (after each use/daily) the equipment and utensils used in the milk collection
- Bottles or buckets
- Source of hot and clean water for cleaning tools
- Thermometer to measure temperature of milk or water
- Tools washing brushes
- Cleaning and disinfecting material for equipment and tools
- Hanger/hanging tool that allows drying of feeding equipment in the open air after sanitizing (exposure to sunlight will also help sanitize the equipment)
- Storage time (from collection to supply) and exposure to sources of contamination
- Storage temperature. The need to heat the milk to a temperature not exceeding 38oC will be evaluated.
- Facilities for pasteurization of liquid foods
- Supply frequency: once to twice a day
- Cleaning of utensils after each use
- Evaluate the alternative use of another type of disposable or non-marketable milk (pasteurized only) namely:
- Transition (milk produced within the first four days after parturition), waste milk (high risk and need for pasteurization)
- Mastitis or other diseases
- Milk with antibiotic residues
Calves should be fed twice a day during the first three weeks, at the same time, each day, preferably in the early morning and a second time, preferably in the afternoon or evening hours, regardless of times scheduled of the milk or the replacement milk supply. In the case of supplying a third time, it is recommended to do it at night.
A feeding program based on the average consumption of 450-500 g of milk replacer per day should be established.
It should be taken into account that the selection of the milk replacers can directly determine the results of the calf’s growth program.
Analysis of nutritional content:
- Protein sources (milk proteins rate and its ratio to total protein content), and other nutrients: fat, vitamins, minerals, fibers, etc.
- Inclusion of additives and antibiotics
- Manufacturer's reputation and quality control of the product
For the use of milk replacers, it is necessary to consider
- Price ratio of milk/milk replacer
- Possibility of storage in dry and clean places
- Equipment and utensils for preparing the milk replacer
- Bottles or buckets
- Bucket for mixing larger amounts of milk replacer
- Source of hot and clean water for cleaning utensils
- Stainless steel whisk for mixing (to avoid lumping)
- Brushes, cleaning materials, disinfection and drying of utensils (cleaning after each use)
Water supply to calves must be carried out, taking into account the requirements of the animals (physiological needs), without counting the water provided by the milk or milk replacer.
- Odorless, colorless and tasteless liquid
- Free access - the location and the height of the water troughs must be taken into account. It is important to avoid the presence of feces and urine around the water source.
- The recommended temperature range is between 10 to25 o C.
- Water consumption: 5-8 liters/day for the first month of life, and 6-10 liters/day for the second month
Different possibilities for dry food supply:
- Total mixed ration (TMR) -18% protein, 1.8 Mcal NEL/ DM with (~12%) or without roughage
- Starter -18-20 % crude protein, 1.85-1.90 Mcal NEL/DM
- Mix of concentrates and high quality hay
In extensive management systems, there is the possibility of using pastures (grazing pastures) or cut grass as a nutritional alternative. This paper does not evaluate this alternative.
It is important to note that ruminal development will occur mainly between 4-8 weeks of life and will depend on the supply of solid food. The way in which solid food is supplied must consider its influence on rumen development (promotion of the papillae growth).
Should one choose to administer starter, it should be noted, that its supply must be from the first day. If this is the chosen practice, the supply of hay will be provided only after weaning, ensuring the use of excellent quality hay.
The choice of the TMR that includes hay as one of its ingredients may:
- Promotes the growth of the rumen muscle layer
- Avoid keratinization of the rumen papillae - abrasive effect (decreased absorption of VFA)
- Activates salivation and rumination process
We may consider that hay intake may limit the concentrate intake, and consequently, reduces the amount of total energy consumed (limits growth). Therefore, it is recommended to limit the amount of hay in the TMR to10-12% of the total DM.
Other factors to take into consideration before considering a feeding method:
- Breed and size of the animal
- Type of the supplied liquid food
- Expected growth rates
- Quality of raw material
- Balanced ingredients
- Content of fermentable carbohydrates that promote the fermentation and production of volatile fatty acids (VFA)
- Presentation form (pellet, mix, flour)
- Climate, housing
To stimulate feed intake, it is recommended:
- Ad libitum supply
- Fresh food must be offered every day (Important: regulation of the supply quantities to prevent food waste and ensure continuous supply)
- Regularly clean feeders
- Availability of fresh water
It is advisable to perform the removing of horns at an early age.
Objectives: Prevent injury and minimize social interference
Methods: Dehorning methods vary by age of animal and stage of horn development.
Can only be used in calves under two months of age:
- Caustic paste. Combination of caustic substances in dehorning paste cauterizes tissue and prevents horn growth. Dehorning paste is applied to the horn buds of calves eight weeks of age or younger.
- Hot iron. An iron is heated to red hot, then held firmly to the horn bud for about 20 seconds, destroying the horn-producing cells and preventing further growth.
- It is highly recommended to perform local anesthesia before treatment by a qualified veterinarian
Mechanical dehorning methods: Some of the available methods are: knife dehorning, tube, cup or spoon dehorning, Barnes or Gouger dehorning, etc.
The mechanical dehorning methods can be used on horns at any stage of development. The dehorning system must be selected taking into account that the intervention does not cause pain or any kind of damage to the animals. For this reason, to select the optimal method for the existing conditions with your animals, we recommend consulting a veterinarian.