The effects of feeding Master Graze (MG) on dairy cows productivity and nutrient digestibility were evaluated in experiment 1. Sixteen cows were divided into 4 groups and fed treatment diets for 4 consecutive periods. Cows on the control diet were fed a diet with corn silage and alfalfa hay as forage source (1:1; DM basis). For treatment groups, the MG substituted the forage mix at 16, 33 and 50%. The feeding of MG at the three tested levels had no effects on feed intake, milk production or milk composition. The apparent digestibility of DM, OM, NDF and CP were higher in cows fed the MG. In experiment 2, the effects of maturity and preservation method on MG nutrient composition and digestibility were evaluated. The MG was harvested at 3 maturity levels and then preserved using oven-dried, ensiled, or freeze dried. In general, the MG digestibility and nutritional quality was higher in the first cut and with the freeze dried preservation method.

The dense and diverse community of microorganisms inhabiting the gastrointestinal tract of ruminant animals plays critical roles in the metabolism and absorption of nutrients, and gut associated immune function. Understanding microbial colonization in the small intestine of new born ruminants is a vital first step toward manipulating gut function through interventions during early life to produce long-term positive effects on host productivity and health. Yet the knowledge of microbiota colonization and its induced metabolites of small intestine during early life is still limited. In the present study, we examined the microbiota and metabolome in the jejunum and ileum of neonatal sika deer (Cervus nippon) from birth to weaning at days 1, 42, and 70. The microbial data showed that diversity and richness were increased with age, but a highly individual variation was observed at day 1. Principal coordinate analysis revealed significant differences in microbial community composition across three time points in the jejunum and ileum. The abundance of Halomonas spp., Lactobacillus spp., Escherichia-Shigella, and Bacteroides spp. tended to be decreased, while the proportion of Intestinibacter spp., Cellulosilyticum spp., Turicibacter spp., Clostridium sensu stricto 1 and Romboutsia spp. was significantly increased with age. For metabolome, metabolites separated from each other across the three time points in both jejunum and ileum. Moreover, the amounts of methionine, threonine, and putrescine were increased, while the amounts of myristic acid and pentadecanoic acid were decreased with age, respectively. The present study demonstrated that microbiota colonization and the metabolome becomes more developed in the small intestine with age. This may shed new light on the microbiota-metabolome-immune interaction during development.

The aim of the study was to determine the digestibility of Atriplex nummularia cv. De Kock, supplemented with three levels (15%, 30%, and 45%) of either maize or barley, using different in vitro techniques. An in vivo digestibility trial was conducted, together with a number of in vitro trials. An important development has been the introduction of biological methods (Jones&Theodorou, 2000). Three digestion techniques that simulate the digestion process are currently available to determine the nutritive value of ruminant feeds: <ol> <li>Digestion with rumen micro-organisms as in the work of Tilley&Terry (1963) or gas method (Menke et al., 1979). Digestion with faeces microorganisms (El Shaer et al., 1987), as an alternative to rumen fluid inoculum.</li> <li>Cellulase methods</li> <li> In situ incubations of samples in nylon bags in the rumen.</li></ol> The results of this study showed no significant difference (P>0.05) between the rumen- and faeces inoculum in vitro techniques, but they did differ significantly from the gas production and cellulase techniques. There was also no significant difference between the gas production and cellulase techniques. Organic matter digestibility (OMD %) of the in vitro techniques differed significantly from the in vivo OMD % values. There are several possible explanations for the difference between the in vivo and in vitro OMD %. 1. Practical mistakes could have been made. 2. The simulation of the rumen motility in vitro is often difficult and it may be that all the feed particles did not have the same exposure to the micro-organisms, as it would have in the rumen of an animal. The different rumen pools are also not fully represented in vitro. 3. The fermentation characteristics and microbial constitution of the rumen inocula differ, between the animal used for the in vivo digestibility trial and the animals used for rumen inocula collection. 4. With in vivo digestibility the time of digestion is not known, and therefore the time of rumen and gastric digestion in vitro could have been too long or too short. It was found that the in vitro faeces technique of El Shaer et al., (1987) is an easier and cheaper alternative to the classic rumen fluid in vitro technique of Tilley&Terry (1963), as modified by Engels&Van der Merwe (1967). The in vitro faeces technique uses faeces as an inoculum and therefore solves the problems associated with the use of cannulated animals. The gas production in vitro technique has certain advantages, but still has the disadvantage of needing cannulated animals for rumen inocula. The cellulase-based in vitro technique in contrast eliminates the use of cannulated animals. Although the in vitro gas production technique of Pienaar (1994) and the cellulase in vitro technique could both be used to determine the OMD % of Atriplex nummularia cv. De Kock, the values will be lower than in vivo determinations. / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Animal and Wildlife Sciences / unrestricted

No abstract available / Thesis (PhD)--University of Pretoria, 1953. / Original thesis in typescript / Includes bibliographical references. / Production Animal Studies / PhD / Unrestricted

Zinc (Zn) has numerous functions and life sustaining processes depend on the presence of Zn within the body. Zinc sulfate is a common form of Zn supplemented in the beef industry. Inorganic sulfate based minerals have been associated with negative rumen effects, mainly, decreased rumen fermentation and protozoa numbers. Our studies concluded no difference in digestibility of three different forms of Zn (zinc glycinate, zinc sulfate, and zinc hydroxychloride). Although overall digestibility did not change, there were specific mineral concentration differences after steers consumed concentrate treatment for 10 days. These differences implied that the mineral fed was consumed and absorbed in post-treatment sample collection of rumen fluid, plasma, and liver. Overall liver Zn levels were within normal ranges and implies the zn fed was absorbed. Based on the results of this study bioavailability of, zinc glycinate, zinc sulfate, or zinc hydroxychloride were similar.

Cattle operations in the Southeastern United States are primarily cow-calf and stocker based and rely heavily on forage. As such, research regarding supplementation strategies that are specific to both the forage cultivars and management strategies that are common in the region are necessary for accurate nutritional recommendations. Additionally, further research is necessary to develop solutions to cope with the negative effects of fescue toxicosis that are common in the region. Therefore, the objectives of this dissertation are to examine supplementation strategies specific to growing cattle as well as to investigate methods of reducing ergot alkaloid intake. Corn gluten feed (CGF) is a common corn co-product that is used to supply supplemental energy and protein. Experiment 1 investigated the effect of supplementing CGF or corn to grazing cattle and found that in grazing situations, growing cattle that are supplemented with CGF have greater average daily gain (ADG) and feed efficiency compared to those supplemented with corn (P  0.03). This improvement in ADG was without changes in subcutaneous fat accretion (P = 0.87), as there were no differences among treatments in fat thickness at the 12th rib (P = 0.54). This improvement in growth and efficiency was thought to be due to differences in the digestibility of fiber in the rumen. Therefore, experiment 2 was designed to investigate the effect of corn or CGF supplementation on apparent total tract nutrient digestibility when cattle are fed a forage-based diet. However, the results from this experiment indicated that there were no changes in neutral detergent fiber digestibility (P > 0.19). In fact, heifers supplemented with corn at 0.25% BW had greater acid detergent fiber digestibility compared with those supplemented with corn at the same level (P = 0.05). Ultimately, this resulted in animals being supplemented with corn tending to have greater organic matter digestibility compared to those supplemented with CGF (P = 0.10). Therefore, the improvement in performance that is observed when grazing cattle are supplemented with CGF compared to corn does not seem to be due to improvements in fiber digestibility. Experiment 3 examined if prolonged storage of ensiled tall fescue would result in the degradation of ergot alkaloids to levels similar to that of hay. Surprisingly, there were no differences among hay or haylage samples for individual or total ergot alkaloids regardless of storage time. Ergovaline concentrations, however, declined after 30 d of storage and were similar throughout the remainder of the storage period. Although no differences were observed among treatments, the reduction of ergovaline concentrations after 30 d of storage indicate that short-term storage may help to reduce the negative effects of fescue toxicosis for the animals consuming it. / Doctor of Philosophy / The Southeastern United States is home to approximately 20% of the country's cattle population and is a major source of feeder cattle that enter the feedlots in the Midwest. The primary nutrient source for cattle in this region is grazeable forage, and production systems in the Southeast are primarily cow/calf or stocker based, with few forage or grain-based finishing operations. Much of the grazeable area is in a portion of the country termed the fescue belt since the primary species of grass is tall fescue. While this species has desirable forage characteristics, it is commonly infected with a fungal endophyte that produces ergot alkaloids that are toxic to livestock. These ergot alkaloids are attributed to billions of dollars of lost revenue and reduced animal welfare. While the forage in the Southeast is of relatively good quality, many producers choose to supplement grazing cattle. This is particularly common during winter months when forage is dormant, and when desired levels of growth exceed what can be provided by forage alone. However, the source of supplemental nutrients can induce changes in the efficiency of forage digestion, and the optimal nutrient source differs when compared to grain-based diets. Therefore, it is important for producers and nutritionists in the Southeast to have access to data relevant to their region of the country. The objectives of this dissertation are to evaluate supplementation strategies relevant for the Southeast, and to evaluate a potential method of mitigating the negative effects of fescue toxicosis in harvested forage. Corn gluten feed has previously been shown to improve performance to a greater extent compared to corn when included in a forage-based diet in a dry-lot setting but has not been investigated in grazing situations. Therefore, we investigated if this effect would be present in grazing situations. Using growing cattle and an automated feeding system, we demonstrated that grazing cattle supplemented with corn gluten feed had greater growth performance compared to those supplemented with corn. To investigate if this was due to differences in nutrient digestibility, we then investigated how total tract digestibility was influenced by supplement type and inclusion level in forage-based diets. However, our results indicated that at relatively small levels of inclusion, total tract digestibility is not impacted by supplement type. To investigate methods to control fescue toxicosis in livestock, we conducted an experiment to determine if ergot alkaloid concentrations in forage harvested as hay and haylage can be reduced through prolonged storage. While there were no differences in concentrations among forage types (hay and haylage), there was a beneficial effect of day for ergovaline concentrations, one of the principal toxins that is present in endophyte-infected tall fescue. This suggests that profits for livestock producers as well as animal welfare can be improved through the short-term storage of harvested tall fescue. Collectively, these experiments demonstrate potential methods for beef producers in the Southeastern U.S. to improve growth in grazing cattle. As researchers continue to improve the understanding of the interaction between grazing livestock and supplementation programs, improved recommendations can be made regarding nutrition programs and ultimately result in a more efficient and profitable operation.

Haemonchus contortus is a blood-sucking abomasal helminth of small ruminants responsible for major economic losses to producers worldwide. Widespread resistance to commercial anthelmintics has created a need for alternative methods of parasite control. One method involves using plant products with natural anthelmintic properties. This thesis assessed the efficacy of several plant products against experimental Haemonchus contortus infection in gerbils and sheep. In gerbil assays, animals were orally infected with 600 third-stage Haemonchus larvae and treated once or daily for 5 days with artemisinin, Artemisia annua aqueous or ethanolic extract, an orange oil emulsion, or Asimina triloba ethanolic extract. Nine days post-infection, gerbils were euthanized, their stomachs removed, and the worms counted. Significant anthelmintic activity was not found for artemisinin, A. annua extracts, or A. triloba extract. The orange oil product caused significant parasite reductions up to 87.8% when administered for 5 days. The orange oil emulsion was tested in sheep to evaluate the product against Haemonchus in its natural host. Sheep were orally inoculated with 10,000 Haemonchus larvae and, one month later, dosed with the emulsion once or daily for 3 days. Fecal egg counts were monitored daily starting on the first day of dosing and continuing to 14 days post-dosing. Results showed that a single dose of the product caused highly significant fecal egg count reduction (97.4%) compared to control sheep and that there is no advantage to treating for 3 days. Thus, the orange oil emulsion shows promise as an alternative to commercial dewormers. / Master of Science

The effect of dietary copper (Cu) supplementation with Cu-Sulfate (CuSO₄) or Cu-Lysine (CuLy) on Cu status and bovine monocyte function was evaluated through a series of experiments. Initially, two in vitro techniques, immunomagnetic (IM) and culture flask adherence (CF), were compared for isolation of a viable, homogeneous monocyte population. The CF technique for monocyte isolation resulted in both a greater number of cells exhibiting phagocytic activity, as well as, an increased phagocytic capacity compared to monocytes recovered by the IM technique. Culture flask adherence appears to be an efficient technique for isolation of a viable, homogeneous population of bovine monocytes. Copper status and monocyte function were evaluated in beef calves supplemented with Cu over a 2 year study period. Fifty-four weaned calves were allotted to one of three Cu treatment groups in a 150 d feeding trial, Plasma Cu concentration was increased in CuLy-supplemented calves over controls and CuSO₄-supplemented calves on d 42, 84, and 126. Calves supplemented with Cu had increased ceruloplasmin activity on d 84, 126, and 150 as compared to controls. Hepatic Cu measured on d 150 was decreased in controls compared to Cu-supplemented calves. Monocyte cell number and function from CuLy-supplemented calves showed increased phagocytosis on d 84 and 126 and increased oxidative burst on d 42 and 126 compared to controls. Dietary Cu supplementation was repeated using 45 calves in a 120 d study. CuLy-supplemented heifers had increased major histocompatibility complex (MHC) class II expression on d 68, 82 and 110 compared to CuSO₄-supplemented and control group heifers. Heifers supplemented with Cu had increased plasma Cu concentrations on d 82 and 110 compared to controls. The effect of vaccination on monocyte function was evaluated in Cu-supplemented beef heifers. Vaccination with B. abortus Strain 19 increased monocyte oxidative burst, phagocytic activity, and MHC class II expression in heifers. Copper supplementation and source of Cu supplement influenced monocyte response to vaccination. Monocyte response appeared to be higher in CuLy-supplemented heifers after vaccination compared to CuSO₄-supplemented and control heifers. / Ph. D.

L’implantation est caractérisée par les premiers contacts cellulaires permanents entre l’endomètre, tapissant l’utérus, et le conceptus (disque embryonnaire et tissus extra-embryonnaires). Cette étape se trouve être l’un des plus importants points de contrôle de la gestation nécessitant un dialogue finement régulé entre ces deux entités. Concernant les ruminants, un déclin de la fertilité a été observé notamment chez les vaches laitières hautes productrices. La moitié des gestations s’arrête pendant la période pré-implantatoire due à des mortalités embryonnaires précoces ainsi qu’à des défauts utérins. Depuis 10 ans, des analyses exploratoires ont été mises en place dans le but d’étudier les profils d’expression de gènes endométriaux sous l’influence du cycle oestral, de la gestation précoce ou encore des stéroïdes ovariens comme la progestérone et les oestrogènes. Ces études sont essentielles pour l’identification des gènes endométriaux clés pour la survie et la croissance du conceptus avant l’implantation. Notre laboratoire a réalisé une analyse transcriptomique à partir d’échantillons endométriaux collectés sur des vaches cycliques et gestantes au 20 ème jour post-oestrus correspondant respectivement à la phase folliculaire et au premier jour d’implantation. Plusieurs familles de facteurs de transcription apparaissent différentiellement exprimées dans cette étude, notamment FOXL2, un membre de la famille des Forkhead Box transcription factor considéré comme le gène clé de la différenciation ovarienne. Ce travail de thèse s’est intéressé à l’implication de FOXL2 dans la physiologie endométriale. FOXL2 est exprimé et régulé pendant le cycle oestral et la gestation précoce dans l’endomètre de ruminants. De plus, la progestérone a été identifiée comme le régulateur majeur de l’expression endométriale de FOXL2 chez la vache et la brebis alors que l’effet des estrogènes n’a pas été démontré. A partir d’une approche gènes candidats, la surexpression de FOXL2 induit la régulation différentielle de onze gènes potentiellement cibles de FOXL2 dans des cultures primaires endométriales de cellules stromales et épithéliales glandulaires. En particulier, PTGS2 qui est un gène impliqué dans la réceptivité utérine apparait inhibé par FOXL2 alors que SCARA5 et RSAD2, tout deux impliqués dans la réponse immunitaire sont stimulés. Enfin, DLX5 apparait différentiellement régulé entre les cellules stromales et épithéliales glandulaires sous l’impact d’une surexpression de FOXL2. Pour conclure, l’expression endométriale de FOXL2 est fortement liée au processus de réceptivité utérine qui se déroule avant l’implantation et peut moduler l’expression de gènes endométriaux essentiels. De nouvelles analyses sont nécessaires pour déterminer si FOXL2 est le gardien de la physiologie reproductive femelle. / Implantation is characterized by the first permanent cellular interactions between the endometrium, lining the uterus, and the conceptus (embryonic disk and extra-embryonic tissues) and appears to be one of the most important checkpoints of successful pregnancy. Regarding ruminant species, and more specifically dairy cows, half of pregnancies abort during the pre-implantation period due to early embryonic death and uterine defects. In the last decade, exploratory approaches have been developed to study endometrial genes expression under the influence of oestrous cycle, early pregnancy, and ovarian steroid hormones in order to identify systematically crucial endometrial genes for conceptus growth and survival leading to a successful implantation in ruminant specifically. A microarray analyse made at the laboratory based on endometrial samples collected from cyclic and pregnant cows at 20 days post-oestrous, corresponding respectively to the follicular phase and the implantation initiation. Several members of the transcription factor families appeared to be differentially expressed in this study including FOXL2, a member of the Forkhead box L sub-class originally considered as a key gene for ovarian differentiation. My PhD thesis focused on the implication of FOXL2 gene in endometrial physiology. FOXL2 gene had been demonstrated to be expressed and regulated during the oestrous cycle and early pregnancy in ruminant endometrium. Moreover, progesterone was identified as a master regulator of FOXL2 endometrial expression in both cattle and sheep whereas estrogens have no impact. Based on candidate genes approach, over-expression of FOXL2 gene induces a regulation of eleven putative FOXL2 target genes in primary endometrial stromal and glandular epithelial cells. In particular, PTGS2 which is a positive regulator gene for uterine receptivity was shown to be inhibited whereas SCARA5 and RSAD2 expressions that were involved in immune response were shown to be stimulated as well as DLX5 expression was differentially regulated between stromal and glandular epithelial cells. Collectively, FOXL2 endometrial expression is strongly linked to the uterine receptivity process prior to the implantation and modulates the expression of essential endometrial genes. Further investigations will be required to investigate whether FOXL2 is the gatekeeper of female reproduction in the vertebrate species.

Le ruminant est exposé aux POP déposés sur les prairies. Cette thèse étudie le transfert des PCDD/F, PCB et HAP du fourrage et du sol vers le lait. De l’herbe contaminée en PHE, PYR et B[a]P a été incubée dans le rumen des vaches pour déterminer la disparition in sacco des HAP, des alcanes cuticulaires et de la MS. Les 3 HAP ont disparus (83%) au bout d’1h d’incubation, tandis que les alcanes cuticulaires et la MS ont présenté une disparition plus lente. Les FT des HAP de l’herbe et du sol vers le lait a été étudié in vivo chez la chèvre. Les HAP natifs sont très faiblement transférés vers le lait quelle que soit la matrice d’apport. Le transfert des PCDD/F et PCB du foin contaminé vers le lait a été aussi étudié. Les FT des PCB ont varié de 5 à 90% et pour les PCDD/F de 1 à 40%. Le risque d’exposition de l’homme via le lait peut se présenter notamment pour les PCDD/F et PCB. Les normes actuelles sur les teneurs de HAP dans le lait ainsi que la toxicité du 1-OH-PYR devraient être précisées / Ruminant is exposed to POPs deposited on grasslands. This thesis study the transfer of PCDD/Fs, PCBs and PAHs from fodder and soil to milk. PHE, PYR and B[a]P contaminated grass was incubated in the rumen of cows in order to determine the in sacco disappearance of PAHs, cuticular n-alkanes and DM. The 3 PAHs disappeared (83%) in the 1st hour of incubation while the cuticular n-alkanes and DM disappearance was slower. The transfer of PAHs from grass and soil towards milk has been studied in vivo in goats. The transfer to milk of native PAHs is minimal whatever the matrix ingested. The transfer of PCDD/Fs and PCBs from contaminated hay to milk has been also studied. The CORs of PCBs varied from 5% to 90% and for PCDD/Fs from 1% to 40%. The risk of human exposure via milk could become meanly with PCDD/Fs an PCBs. The current safety threshold values in milk as well as toxicity of 1-OH-PYR must be reviewed