Getting it right when rearing cattle

Research now 60 years old showed that poorly-reared young stock will carry this burden into later life.  It's a familiar picture. You see poorly reared calves that become poor yearlings which end up as unproductive mature stock.

Aim

To get young stock to grow from weaners to yearlings to reach their optimal target weight for mating and calving.

Good signs

• Good weaned calves that keep on growing averaging close to 1kg/day up to yearlings.
• No health or ill-thrift problems with minimal veterinary costs.
• Animals that start cycling well before 12 months of age.

Bad signs

• Poorly grown, miserable looking rising yearlings too small for mating.
• High death rates (above 3%) from weaning to yearling stage.
• Permanent scouring blamed on worms.
• No animals showing oestrus.

Animals grazed on outside farms

Grazing young stock on contract off the farm is now the common practice. It has the advantage of allowing greater production on every hectare of the main farm through greater stocking rates of lactating animals.

The disadvantage is that management of the stock is in the hands of the grazier. It's important that the owner builds performance targets into the contract but many farmers don't do this and trust the grazier. Animal health is extremely important as where a grazier runs stock from different owners, then cross infections can occur, e.g. with drench resistant internal parasites.

Target weights

Success is about making sure animals have reached their target weights. Remember that a target weight is the weight every animal in the group should reach. It is not an average weight for the group. Here are some currently accepted target weights in New Zealand.

Age	Jersey (kg)	Holstein-Friesian (kg)
Birth	25	35
Weaning (8-10 wks)	65-75	80-90
6 months	110	135
12 months	190	235
15 months	230	285
18 months	270	335
24 months (pre-calve)	400	490
24 months (post-calve)	335	435
Birth - 2 years (post-calve)	0.46kg/day	0.56kg/day

Chest girth measurements

If you can't beg, borrow or hire some scales, then chest girth measurements are a last resort, because there is a lot of variation within animals of different size and they cannot take into account body condition (fatness).  Only use chest girth on calves, and even then, don't buy calves on a per kg live weight using this measure.  Here are some values as a rough guide.

Weight (kg)	Chest girth (cm)
50	85-87
100	100-105
150	115-120
200	135
250	145

Fast and slow growth -which is better?

Unlike beef cattle where you want maximum "weight-for-age" all the time, research many years ago showed that dairy heifers should not be grown too fast and "fattened". The old teaching wasthat too high a feeding level produces fat in the developing udder tissue, which reduces milk production later in life.

The key aim is to get heifers to grow fast enough to reach puberty at around 12 months of age and start coming on heat at 15 months old. Puberty is more controlled by weight than age, but there are exceptions such as well-grown Holstein-Friesian heifer calves coming on heat at 4 months old.

After heifers get pregnant, feeding level doesn't influence udder development, and reaching target weight for first calving is very important, as this influences lactation and oestrous afterwards.

Heifer growth targets

Here's a table of target live weights based on the mature weight of cows in the herd. It makes a lot more sense than just having one target weight, as it takes into account different breeds and farming conditions.  Fifteen months is a mating weight and 24 months is a calving weight.

Mature Wt	Target Wt	350kg	400kg	450kg	55kg	550kg	600kg
6 mo	30%	105	120	135	150	165	180
15 mo	60%	210	240	270	300	330	360
22mo	90%	315	360	405	450	495	540

Feeding levels to achieve good weights

This table shows Dry Matter (DM) intakes to achieve different targets.

Targets	0.4kg/day	0.6kg/day	0.8kg/day
For 100 kg LW	3.4kg DM	4.3kg DM	6.3 kg DM
For 200 kg LW	4.6	5.5	6.3
For 300 kg LW	5.6	6.5	7.4
For 400 kg LW	6.6	7.4	8.3
For 500 kg LW	7.5	8.3	9.2

Internal parasite control

It's more important than ever before, that before you decide to drench cattle for worms, that you talk to your veterinarian to get a correct diagnosis of the problem. Just buying drench for stock where their problem is not worms will only increase the chances of accelerating drench resistance in the worms.The same comments relate to external parasites (mainly lice) too.