At Chemuniqué, we are proud to use global knowledge, strengthened by local research and expertise, to produce feed for food for the future. Catch our team in action at this year’s Poultry Science Association (PSA) Annual Meeting in Montréal, Canada. Both Dr Peter Plumstead and Micaela Sinclair-Black will present at the Symposium: Recent Advances in Calcium Nutrition of Broilers and Layers on Thursday 18 July.

Dr Peter Plumstead completed his BSc (Agric) honours degree at the University of Pretoria, and MSc and PhD degrees in nutrition and poultry science from North Carolina State University in the USA. He has a diverse range of experience, both as a research scientist and in applied aspects of poultry nutrition and management, and currently serves as the technical director Chemuniqué, an Adjunct Associate Professor at the University of New England, and as a global nutrition consultant with a focus on the application of management and nutritional strategies that improve the efficiency of poultry production. His presentation is entitled: “Predicting limestone calcium digestibility and impact on phytase efficacy: Where are we?” Recent research has shown that geological differences in limestone rock, as well as differences in the particle size of limestone, result in large differences in ileal calcium digestibility in broilers in vivo. Further, as a result of interactions of calcium with phytate, the characteristics of the limestone used in feed formulation also affect ileal phosphorus digestibility and the contribution of phosphorus and calcium from exogenous phytase enzyme supplemented to feed. “Our research focus has been the development of a dynamic model that could predict observed differences in calcium and phosphorus digestibility from an in vitro assessment of limestone quality, together with other influential factors,” he says. “Results to date have shown that including limestone solubility at multiple time-points in a model was able to describe more variation in observed calcium and phosphorus digestibility than solubility at a single time-point. Important interactions of limestone characteristics with phytate level, phytate source, and added phytase are still required to be included in the final dynamic model that can be used to predict digestible calcium from limestone, as well as the expected contribution of calcium and phosphorus from exogenous phytase.”

Micaela Sinclair-Black completed a BSc (Agric) honours degree in animal science at the University of Pretoria in 2017 and is currently in the process of earning a master’s degree at the same university. She is employed at Chemuniqué as an intern in the poultry team while she completes her research on calcium and phosphorus digestibility in laying hens. In 2018, she earned academic colours at the University of Pretoria, as well as receiving the Koos van der Merwe award as the AFMA Student of the Year. She is presenting on calcium and phosphorus digestibility as affected by time after oviposition in laying hens. “Laying hens undergo intense physiological changes throughout the day as medullary bone remodelling and eggshell formation occurs, and these changes result in the hen requiring different quantities of calcium from her diet at different times,” she says. “Limestone provided in the diet contributes over 90% of this calcium requirement of the hen.” Dietary calcium and phosphorus digestibility is greater 13 hours post-oviposition during the time the egg is in the shell gland compared to three hours post-oviposition when medullary bone replenishment is occurring, and the change in ileal calcium and phosphorus absorption is likely modulated by shifts in parathyroid hormone (PTH) and 1,25 (OH) vitamin D3. “Higher particle size limestone can have greater benefits in increasing ionisable blood Ca during shell formation,” she says. “Based on this, the time of day, reproductive status, and limestone particle size can be influential in Ca and P digestibility.”

By applying great science, Chemuniqué challenges the boundaries of accepted practice with a spirit of creativity and innovation. We believe in broadening the frontiers of what is possible today, to meet the nutritional needs of tomorrow. We are passionate about people, personal relationships, about the animals we work with, and great science.

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