Masters Degrees (Animal, Wildlife and Grassland Sciences)

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Browsing Masters Degrees (Animal, Wildlife and Grassland Sciences) by Advisor "Einkamerer, Ockert Bernard"

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    The effect of milk replacers containing fermented plant protein and a higher carbohydrate content on the growth performance and profitability of Holstein bull calves
    (University of the Free State, 2025) Kriel, Elsa Ena; Einkamerer, Ockert Bernard; van Zyl, Johannes Hendrik Combrink
    𝑬𝒏𝒈𝒍𝒊𝒔𝒉 The objective of this study was to evaluate the biological and economic viability of alternative milk replacers for Holstein bull calves, focusing on high-carbohydrate and fermented plant protein-based formulations. The primary goals were to assess the impact of these alternatives on calf growth, health, and profitability by identify the most cost-effective options for farmers. 𝗖𝗵𝗮𝗽𝘁𝗲𝗿 𝟯 investigate the effects of fermented plant protein (FP) and increased carbohydrate (HC) levels in milk replacers on calf growth performance. Four different milk replacers were formulated: a conventional replacer (A), one with 20% fermented plant protein (B), a high-carbohydrate replacer (C), and a high-carbohydrate replacer with 20% fermented protein (D). These milk replacers were tested in a 77-day trial (TP, total phase) involving 32 Holstein bull calves, which were randomly assigned to four treatments (n = 8). The trial was divided into two phases: Phase 1 (P1, days 0–63), where milk replacers were fed, and Phase 2 (P2, a two-week post-weaning period), designed to evaluate weaning shock. Milk replacer intake was controlled, while starter meal intake was offered 𝘢𝘥 𝘭𝘪𝘣𝘪𝘵𝘶𝘮. Growth performance metrics such as weight gain, dry matter intake (DMI), average daily gain (ADG), DMI as a percentage of body weight (DMI/BW%), and feed conversion ratio (FCR) were analysed using a factorial ANOVA. An interaction was observed for TP FCR (P = 0.036). Except for controlled milk replacer intake and P2 DMI/BW% and P2 FCR, milk replacers containing FP generally resulted in poorer performance (P < 0.05) compared to milk replacers containing standard protein (SP). The lower performance was attributed to the higher levels of trypsin inhibitors present in the FP, which negatively impacted calf growth. High-carbohydrate milk replacers promoted greater starter meal intake during all phases (P < 0.05) and is recommended. Fermented protein should only be considered when the fermentation process is improved to reduce trypsin inhibitor levels to below 4 mg/g of protein. 𝗖𝗵𝗮𝗽𝘁𝗲𝗿 𝟰 shifts focus to the financial analysis, comparing the cost-effectiveness of the different milk replacers (A, B, C and D). Financial parameters such as total cost, average daily cost (ADC), cost per weight gain (Cost/WD), and income from the sale of calves were assessed. In terms of overall cost and ADC, treatment D was the most economical, with a total feeding cost of R2739.40 per calf for TP. However, when factoring in feed conversion ratio (FCR), treatment C was the most costeffective, with the highest income and lowest cost per unit weight gain (R58.83), although not significantly different when compared to Treatments A and D. 𝗖𝗵𝗮𝗽𝘁𝗲𝗿 𝟱 extends the financial analysis by exploring the use of girth circumference weight estimation tapes as an alternative to expensive electronic scales. This method is valuable for calf management, as weight is crucial for feed management and medication protocols. The study found that while the specific tape used in the trial overestimated calf weights, it holds potential as a lowcost alternative, with further refinement needed. The data collected can contribute to the development of a larger database to improve future weight prediction tools. 𝗜𝗻 𝗰𝗼𝗻𝗰𝗹𝘂𝘀𝗶𝗼𝗻, this study demonstrates that high-carbohydrate milk replacers are a viable and costeffective alternative to conventional formulations, offering potential cost savings without sacrificing calf growth performance. While fermented plant protein showed promise as a cost-effective protein source, its effectiveness in this trial was reduced by the presence of trypsin inhibitors, which could be addressed through improved processing methods. Additionally, Chapter 5's exploration of girth circumference measurement as a cost-effective weight estimation tool further supports the economic viability of alternative approaches to calf rearing. The findings highlight the need for ongoing research to optimize these alternatives and improve profitability in the dairy industry. ___________________________________________________________________