Glycerine: Bridging the energy deficit in early lactation.

ICBF data, reports a marked increase for February calf registrations, as the 2019 calving season kicks into action. However, figures are still 8-9 percent behind the same period as last year, as many farmers chose to delay the 2018 breeding season in order to calve closer to the spring grass wedge. These decisions, taken in the hope of avoiding any unseasonal weather conditions this spring, have resulted in a 2-3 week delay on calving dates.

Good animal husbandry practices are essential at calving, and help negate some of the metabolic and environmental changes occurring during the cow’s transition to early lactation. Feed intakes, for most cows’, are only 8-10kg dry matter (DM) in the immediate week post calving, and are not sufficient to support both milk production and body maintenance. These low intakes, inevitably result in the cow entering a period of negative energy balance (NEB). This nutritional imbalance is most acute in the first 6 weeks post calving and is not fully bridged until peak dry matter intakes (DMI) return in the 10th – 12th week of lactation. Although affordable for most cows in good body condition score (BCS), high yielding, over fat and poorly conditioned cows are at a higher risk of developing underlying metabolic diseases and reproduction failure if the (NEB) is not addressed quickly.

Cows of (BSC) of 3.5 or greater are most susceptible to metabolic diseases in early lactation, with ketosis being one of the main offenders. Already having a low (DMI), these overfat cows mobilise large amounts of their own body reserves for milk production. This fat, is then transported as none esterified fatty acids (NEFAs) to the liver and broken down to release energy. Due to the large increase of fat mobilisation, the cow’s liver becomes saturated and metabolites known as ketones are produced. These ketones then overflow into the bloodstream, resulting in a further reduction in the cow’s appetite and subsequently a reduction in her milk yield. It is at this point that the cow is on the verge of ketosis. Diagnosis of cows with ketosis generally occurs 2-4 weeks post calving and this usually indicates that there is a larger underlying ketosis problem within the herd.

Cows of higher genetic merit can also suffer from increased incidence of ketosis. Experiencing a rapid increase in milk production, accompanied by a slow rise in (DMI), high yielding cows inevitably succumb to a nutritional imbalance. These conditions unavoidably result in cows entering a period of (NEB). If the (NEB) is allowed to persist, large amounts of the cow’s own body reserves will again be mobilised, thus, facilitating the perfect environment to exist for the onset of ketosis.

Applying correct management practices in the dry period prior to calving can greatly reduce a cow’s susceptibility to ketosis. Body condition score management is vital, cows should calve down in a fit state and not over fat with a (BCS) of 3.0-3.5 being the optimum. Additionally, minimising cow stress levels, avoiding any sudden dietary changes and maximising cow (DMI) post calving are all practices that can help offset the frequency at which these metabolic diseases might occur.

Supplementing with a quick acting glucose solution in the form of glycerine is also an excellent management technique that can be used. Having an energy content of 1.6 UFL/kg/DM, glycerine is the ideal supplement to help counteract any nutritional imbalance that occurs in early lactation. Additionally, glycerine also increases overall water consumption as well as acting as an excellent glycogenic precursor, which is an important constituent for milk synthesis. Having such a high energy density, allows for low inclusion rates of glycerine in the overall diet, therefore, not effecting overall rumen fill. Moreover its versatility allows it to be dosed through liquid feeders on robotic milking machines, mixed through the total mixed ration (TMR) or topped dressed on forages.