Dairy R&D in SA

M. van Niekerk, a student from South Africa, reported genotype x environment interaction in SA Holstein dairy cattle, clear differences being seen in genetic parameters between herds using a total mixed ration (TMR) or pasture-based system. Specifically, genotype by environment interaction for persistency of production between the two production systems were indicated with genetic correlations for the first three lactations of below 0.64 throughout.

Dairy farming is a water-intensive land use and one which can degrade water quality. Examples of potential impacts include:

1. Viability of Bifidobacterium species in probiotic yoghurt as influenced by reducing agents.

The camera frame was deployed at the University of Pretoria experimental farm. The frame was placed over the crush above the weighing platform. Three 3D cameras were used to capture the cow body from different angles – top, rear, angled – in order to obtain enough body information. During the course of the investigation several changes were made to the system and the data collection procedure to ensure the process went smoothly and as much of the collected data was accurate and usable as possible.

Age gelation is a process in which there is formation of a three-dimensional protein network within UHT milk which occurs during storage, and is marked by increasing viscosity before observable gelation. In South Africa, the dairy industry loses millions of Rands annually as a result of the condition in UHT milk. As such, there is a need to study and evaluate the possible correlation of variables that may contribute to the occurrence of age gelation in UHT milk.

Conception and re-conception rates of high-producing dairy cows remain of concern in dairy production systems, especially in the subtropics. Apart from the major effects of nutrition and specific nutrients on reproduction, other risk factors such as negative energy balance, inflammation and impairment of the immune response have been shown to affect re-conception rates. Dietary energy levels interact with blood urea nitrogen (BUN) and may influence the pregnancy rates of dairy cows.

Kikuyu-ryegrass may no longer be optimum in the south-eastern Cape because of a number of reasons:
•    Extended periods of lower than expected rainfall
•    Poor persistence of ryegrass, with a decline of as much as 44% reported in even the most productive ryegrass cultivars from year one to year two

Discipline: environment; Keywords: GHG, emission reduction, net zero, carbon sequestration, systems dynamic model, dairy production systems. 

There is reason to believe that diurnal patterns for enzymatic activity exist, as bacterial numbers have been shown to be influenced by time of feeding. Also, when performing ruminal in vitro studies, little attention is given to the time of day when rumen fluid is sampled, thereby not controlling variation caused by diurnal patterns and the effect it might have on starch, NDF, and protein digestibility. Additionally, often results are compared between in vitro studies without considering time of rumen fluid collection or feeding time.

Heat stress is defined as an event that affects an animal’s homeostasis and health owing to a physiologically harmful heat load. Heat stress may prompt physiological dysfunction, which affects an animal’s production and reproduction capacity negatively, and causes economic losses that are estimated to be billions of dollars worldwide. Heat stress also influences a cow’s immune system which may manifest in a higher incidence of udder health problems during summertime.