Caring for the newborn
The long term future of a dairy heifer can be influenced by events in the first 24 hours of her life.
Perinatal mortality can be defined as the death of a calf within the first two days of life, irrespective of the cause of death or circumstances at calving.
This does not include calves born prematurely (prior to 37 weeks). Research from the US suggests perinatal mortality averages 8%, a welfare concern and a big impact on a farm’s subsequent production and profitability. Most perinatal deaths occur in calves that were alive at the beginning of calving, suggesting many of them are preventable. Part one of this series discusses how to reduce perinatal mortality from the beginning of the hazardous journey that is birth.
The stages of labour
Calves that suffer a prolonged or difficult birth (dystocia) are at increased risk of perinatal death and calfhood disease. There can also be a lasting negative effect on subsequent milk production. To help avoid this, it is important to recognise when cows and heifers are in the various stages of labour and to know how long these should be in a ‘normal’ calving.
Stage 1 (3-6 hours)
The first stage of labour can vary greatly amongst individual animals and the changes happening within the body are not clearly visible from the outside. During this stage the muscles within the walls of the uterus are beginning to contract and the cervix is progressively dilating with each contraction. The contractions may initially be 15 minutes apart but by the end of stage 1 should be about three minutes apart. The mucoid plug, which has existed in the cervix during pregnancy, is expelled and the vaginal discharge becomes more liquid. From the outside, stage 1 labour can be observed as separation from the rest of the herd, tail lifting and swishing, mild kicking of the belly, increased frequency of lying down and getting up and the presence of a ‘water bag’. An examination should be done if abdominal contractions (stage 2, see below) have not begun after six hours, although this first stage of labour may be prolonged in heifers (up to 12 hours).
Stage 2 (30 minutes - 4 hours)
As a cow or heifer enters the second stage of labour her cervix should be fully dilated and there should be visible abdominal contractions (‘straining’). During this stage, the ‘water bag’ breaks and the calf enters the birth canal. In a normal delivery the calf should be positioned head-first along with both front legs (a ‘diving’ position).
The cow or heifer may lie down during stage 2 due to increasing pressure in the birth canal and pain from contractions. As the calf is expelled the membranes over the head of the calf should rupture, allowing the calf to breathe for the first time. Although the duration of stage 2 labour is variable it is advised that animals are examined after two hours if there has been no visible progress.
Stage 3 (2-12 hours post-calving)
In this final stage of labour, the foetal membranes or placenta are completely expelled.
Knowledge of these various stages of labour allows early intervention and assistance if necessary. Consequently, this will help in the more rapid and safe delivery of the calf and improve survival of both calf and cow.
• Dr Gemma Chuck is a dairy vet at The Vet Group, south west Victoria.
