A novel clinical assay for the assessment and subsequent treatment of Haemonchus infection in sheep to slow down the development of anthelmintic resistance – the FAMACHA / Dissertation (MSc)--University of Pretoria, 2001. / Veterinary Tropical Diseases / unrestricted

Thesis ( (M.Sc. Agriculture (Animal Production)) -- University of Limpopo, 2019 / A lack of energy and water in livestock production limit the performance of the animal. Therefore, the objective of this study was to determine the effect of spineless cactus as a source of energy and water on feed intake, feed digestibility and milk production of Holstein cows. Cactus serves as fresh forage or stored as silage for later feeding in livestock. However, there is limited information about cactus nutrients, their proportions in different species and the variability of these proportions with season. A total of four multiparous lactating Holstein cows with an average of 650 ± 80kg live weight were used and assigned to four dietary treatments with four replicates. Each animal was used four times. A cross-over design was used. The four dietary treatments were 0%, 4%, 8% and 12% of spineless cactus meal inclusion levels. The study period was 21 days of adaptation period and 6 days of collection period. Higher digestibility and energy supply (P<0.05) were observed with spineless forage diets compared to the control diet. Inclusion of spineless in the diets improved (P<0.05) diet intake and milk production in Holstein cows. However, an improved performance in milk production was observed with spineless cactus meal inclusion levels of 4%, 8% and 12%. Amongst the diets, 0% inclusion level had lower dry matter intake of 22.7kg (P<0.05) compared to those which had spineless cactus meal. High dry matter intake resulted in higher (P<0.05) milk production of 22.7, 24.7, 23.4 and 23.8 litres for 0, 4, 8 and 12% spineless cactus meal inclusion levels, respectively. However, cows on 4% inclusion level had higher milk yield than the other diets. Milk quality (butter fat, protein, lactose, somatic cell count and milk nitrogen urea) of Holstein cows was not (P>0.05) affected by the level of spineless cactus meal inclusion in the diet. Dry matter intake, neutral detergent fibre intake, acid detergent fibre intake and metabolisble energy intake of the cows were optimized at different spineless cactus meal inclusion levels of 19.427% (r2 = 0.992), 16.375% (r2 = 0.974), 14.0% (r2 = 0.984) and 22.909% (r2 = 0.994), respectively. Spineless cactus meal inclusion had no effect (P>0.05) on ADF intake and crude protein intake. Apparent digestibility values (0.73, 0.76 and 0.76) were not significantly different at 4%, 8% and 12% of spineless cactus meal inclusion levels, respectively. v It is concluded that spineless cactus meal inclusion level in the diet affected (P<0.05) diet intake and milk production of the Holstein cows. However, these variables were optimized at different spineless cactus meal inclusion levels. It could be recommended that spineless cactus can fit perfectly in livestock rations with attention given to their low crude protein content. These opuntia species can be fed to livestock mainly cattle and sheep during any season but are needed the most during drought as supplements when forages are scarce or expensive to feed. It is, therefore, concluded that 8% of spineless cactus inclusion level can be used to maintain productivity of the animals. / National Research Foundation (NRF)

Die Beziehungen zwischen der Reproduktionsleistung und der Körperkondition wurde in zwei Experimenten mit Awassi Schafen im Libanon untersucht. Im ersten Experiment wurden 72 Schafe in drei Altersklassen (Zutreter, primipare und multipare Mutterschafe), in zwei Körpergewichtsklassen (leichte, schwere) eingeteilt und jeweils zwei Fütterungsgruppen (ohne und mit Zufüterung) zugeordnet. Primipare und multipare Mutterschafe der Zufütterungsgruppe wiesen höhere Körperkondition, gemessen als BCS (p / The relationship between reproductive performances and body condition has been studied in 2 experiments using Awassi sheep in Lebanon. In the first exp., 72 experimental animals were grouped according to age (ewe lamb A, primiparous P, multiparous M), to body weight into small weight (SW) and large weight (LW), and kept under two management systems: traditional and improved (barley supplement). Primiparous and multiparous ewes showed a higher BCS (p

<p dir="ltr"> Improving feed efficiency in beef cattle is essential to meet rising global beef demand while reducing costs and environmental impacts. Genetic selection plays a significant role in identifying and breeding more feed-efficient animals, with multi-population data integration enhancing prediction accuracy. To optimize animals for selection or breeding programs related to efficiency, it is crucial to understand the traits associated with mature cow size and the genetic relationships between them. Mature cow size, defined by mature cow weight (MWT), height (MHT), and body condition score (BCS), is pivotal to cow-calf profitability, maintenance efficiency, and reproductive performance.<br><br> The objectives of the first study were to: 1) estimate variance components and genetic parameters for MWT, MHT, and BCS in the United States (US) and Australia (AUS); 2) estimate genetic correlations between mature cow size traits and early growth and carcass traits; and 3) estimate the genetic correlations among these traits across the two countries. The datasets provided by the American Angus Association and Angus Australia included 434,746 and 206,003 records for MWT, 213,875 and 15,379 records for MHT, and 382,156 and 36,184 records for BCS, respectively. Single-trait repeatability models were used to estimate heritabilities and variance components. Multiple-trait models were used to estimate phenotypic and genetic correlations between traits and across countries. Heritability estimates for MWT (US: 0.45; AUS: 0.40), MHT (US: 0.57; AUS: 0.63), and BCS (US: 0.18; AUS: 0.18) highlighted moderate-to-high genetic control. Genetic correlations within the US and Australian datasets between MWT and MHT, and MWT and BCS were > 0.50, and < 0.20 between MHT and BCS. Genetic correlations between MWT, MHT and early growth traits were generally positive and moderate-to-high, ranging from 0.51(0.01) to 0.92(0.003) in the US and 0.41(0.03) to 0.79(0.05) in Australia. Genetic correlations between the traits in the two countries were high for MWT = 0.91 (0.02) and MHT = 0.98 (0.02); and moderate for BCS = 0.65 (0.08). The results suggested that optimizing selection for mature cow traits is feasible, and that a joint evaluation between the US and Australia could be beneficial. </p><p dir="ltr"><br></p><p dir="ltr"> The objective of the second study was to investigate the impact of different modeling approaches on the estimation of breeding values for MWT, with a focus on how BCS was treated across models. The dataset provided by American Angus Association comprised 382,156 MWT and BCS records from 209,491 cows. Four modeling approaches were evaluated: Model 1 did not consider BCS; Model 2 treated BCS as a categorical fixed effect; Model 3 used pre-adjusted records standardized for BCS and age; and Model 4 used a recursive model to assess MWT as a genetically independent trait from BCS. Spearman correlations between models ranged from 0.78 to 0.95, with model choice influencing sire rankings by 5–22% and top 10% concordance differing by up to 40%. Model selection can significantly affect rankings, highlighting the importance of carefully selecting the model that aligns best with the breeding goals. The recursive approach appears to effectively derive MWT that is genetically independent of BCS. </p><p dir="ltr"> This thesis analyzes genetic relationships among mature cow size traits; mature cow weight, height, and body condition score, providing insights for selection programs aimed at optimizing cow’s efficiency. Through variance analysis and genetic correlation studies across North American and Australian Angus populations, it highlights the potential of joint evaluations across countries. It also assesses how different modeling approaches for estimating breeding values for mature cow weight can affects sire rankings and selection decisions, underscoring the importance of model alignment with breeding objectives. Ultimately, this work contributes to the goal of a more sustainable beef industry, where mature cow size is optimized.</p>

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