Agri Kultuur September / September 2015 | Page 50

Heifers should preferably be weighed at least once a month. Their body weight should be recorded and compared to an ideal growth curve in order to make adjustments in the feeding programme if necessary. In Table 4 the suggested girth (chest) circumference, live weight and shoulder height of heifers of various dairy breeds at specific ages are presented. In closing  Heifers should be grouped according to age, especially when they are being fed. Age differences within any one group should preferably be limited to a maximum of two months. The reason for this is that smaller heifers are intimidated by larger heifers, with the result that their voluntary feed intake is reduced.  Heifers do not require sophisticated or expensive housing. However, grouping them in small paddocks should be prevented as the ground surface quickly becomes wet and dirty. Protection against extreme temperatures and particularly the provision of shade on hot summer days are essential.  Correctly designed and well built Age (months) Birth 1 2 4 6 8 10 12 14 16 18 20 22 24 feed troughs should be provided for feeding heifers in order to prevent injuries and feed wastage. Fit trough space to the size of heifers within each specific age group, i.e. 600 mm for older heifers.  Calves and heifers should be weighed or measured regularly, at least monthly, in order to monitor their development and growth. A growth curve of each heifer’s live weight gain in comparison to her age at weighing should be kept. By comparing the live weight gain of heifers to an ideal growth curve, the efficiency of management can be monitored. This will ensure that adjustments to feeding programmes, amongst other things, could be made well in time before they have a lasting detrimental effect on the animal’s growth and performance.  Heifers should be treated calmly and quietly with workers moving amongst them daily. This should particularly be done during the last three months before the expected calving date. If practically possible, heifers should be introduced at an early age to the milking parlour environment so Girth (mm) Holstein Live weight (kg) Shoulder height (mm) 735 810 915 1 120 1 270 1 400 1 500 1 575 1 640 1 690 1 730 1 780 1 815 1 865 40 58 77 113 150 186 223 259 302 344 387 429 472 515 635 785 865 990 1 065 1 120 1 170 1 220 1 245 1 270 1 295 1 320 1 345 1 370 that they become familiar with the facilities and daily routine. This can be done by keeping the heifers with dry cows in late pregnancy, i.e. the steam-up group. Usually these cows are fed a specific steam-up dairy meal in the milking parlour. This means that they visit the dairy at least twice a day. A wild, uncontrollable heifer at first calving suffers enormous stress, and this could be extremely detrimental to her production during her first lactation while also affecting the mood in the milking parlour upsetting other cows.  Before the age of one month, heifer calves should be dehorned with a branding iron and extra teats should be removed.  A vaccination and immunisation programme, compiled in collaboration with a local veterinarian, should be followed according to instructions.  Vaccinating heifer calves against contagious abortion (Brucellosis) at five months of age is compulsory by law and is also essential because the cows cannot be vaccinated for this disease at a later stage. Ayrshire/Guernsey Live Shoulder Girth weight height (mm) (kg) (mm) 660 810 1 105 1 145 1 270 1 400 1 475 1 525 1 575 1 625 1 675 1 700 1 750 32/30 47/44 62/57 93/85 123/112 154/140 184/167 215/194 251/228 288/261 324/295 360/328 397/361 434/395 685 760 815 915 990 1 040 1 090 1 145 1 170 1 195 1 220 1 245 1 270 1 295 Girth (mm) Jersey Live weight (kg) Shoulder height (mm) 785 965 1 120 1 220 1 320 1 410 1 475 1 510 1 550 1 600 1 625 1 675 25 37 49 74 98 122 147 171 202 232 263 293 323 354 660 685 760 865 965 1 015 1 065 1 090 1 120 1 145 1 170 1 195 1 220 1 245 Table 4. The suggested girth circumference, live weight and shoulder height of replacement heifers growing at the lowest live weight gain for different dairy breeds