Genetic Characteristics and Recessives
Holstein Australia aims at providing dairy farmers with information regarding potential carriers of desirable genetic characteristics and undesirable genetic defects (or recessives) that have a negative impact on the breed. By advising of these animals at registration, owners are able to make decisions regarding their future breeding with the aim to increase desirable characteristics while eliminating and/or minimising defective genes in their progeny.
Genetic characteristics
Polled
Polled refers to the absence of horns or scurs in an animal.The trait of being polled in dairy cattle is in fact dominant meaning that an animal only needs to get one polled gene from its parents. This is referred to as heterozygous and animals are coded PO (breeder observed) or PC (tested confirmed). Animals with two copies of the polled gene are referred to as true polled or homozygous and are coded PP (tested confirmed).
A1 A2
A1 A2 refers to the presence of A1and A2 proteins in milk. Animals tested to be true A2 only have the A2 protein in their milk and are coded A22.
Genetic recessives
BLAD is a genetic metabolic disease of cattle known as Bovine Leucocyte Adhesion Deficiency. It affects the animal’s immune system and consequently its ability to fight harmful organisms. This results in high fevers, persistent infections, gum disease, scours and pneumonia. Death usually occurs within a few months of birth or before puberty. Find out more.
Brachyspina
Brachyspina syndrome is a congenital inherited defect that causes physical deformities as well as embryonic death . Affected calves have severally reduced bodyweight and exhibit a shortening of the spine with long and thin limbs.Find out more
Citrullinaemia is caused by a deficiency of arginonosuccinate synthetase (ASS), one of the enzymes of the urea cycle. It is believed that ammonia builds up in the brain of the affected calves because, due to the ASS deficiency, it is unable to be converted to urea for elimination. Calves affected with citrullinaemia appear normal at birth, but within 4-6 days it has died. Signs begin with depression and poor feeding, followed by aimless wandering or standing with the head pressed against a wall or fence. Eventual collapse follows within 12 hours after the symptom of blindness, bellowing and paddling of limbs. Find out more
CVM deficiency is a lethal condition. It causes early abortion due to foetal death or, if the calf survives to term, it usually dies within a week of birth. Its discovery was delayed because the high level of foetal death masked the condition. The reason why that animal failed to calve was that it was just another failed pregnancy, for whatever reason they occur. In this case it was a very good reason. Find out more
DUMPS is a genetic metabolic disease of cattle known as Deficiency of Uridine Monophosphate Synthase. This disease is lethal at the embryonic stage (approximately at day 40 of pregnancy). This means that Carrier females (dam of embryo) show a higher rate of return to service. This is due to natural abortion of the affected embryo. Find out more
In Holstein dairy cattle, the condition of Factor-XI deficiency can cause some cows to have a tendency to bleed. Originally, symptoms noticed in these animals were blood in the milk of recently calved females (i.e. pink colouration of the colostrum). Haemorrhaging or excessive bleeding after calving may also occur. In some cases this is lethal. For other animals, extra bleeding may occur during routine tasks such as de-horning. Another observation of Factor-XI deficient animals has been “compromised” reproduction and may be noted as one that has difficulty getting into calf. The animal may also be deemed as ‘poorly’. Find out more
Mulefoot, also known as syndactylism, is the fusion of the two toes of the foot (resembling a thin mule’s foot. It most often affects the front feet. Although Mulefoot is not a fatal condition, it can affect the mobility of the animal and this impacts on its performance. Find out more