Pharmacological levels of inorganic forms of copper (Cu) and zinc (Zn) are frequently used in diets for pigs to improve performance and control post-weaning colibacillosis. However, the use of such forms and levels causes mineral accumulation in the soil, and is a non-sustainable practice from an environmental perspective. Alternatively, organic complexes of copper (Cu) and zinc (Zn) have been proposed to be more available to pigs, and when included at lower levels than inorganic sources of these minerals have significantly reduced mineral excretion in faeces without compromising performance. However the effect of these organic minerals fed simultaneously at low levels of inclusion has not been well studied. The general hypothesis tested in this thesis was that concentrations of Cu and Zn in faecal material would be reduced when fed in an organic (Bioplex®) form without compromising performance or mineral homeostasis in growing/finishing pigs, in comparison to Cu and Zn fed in an inorganic (sulphate) form. Two experiments were performed to test this hypothesis: Experiment 1 was designed as a 2x2 factorial arrangement of treatments, with two mineral forms (Bioplex® and Sulphate) and two inclusion levels (High and Low). The “low” levels aimed at providing 80 mg/kg of dietary Cu and Zn, and the “high” levels aimed at providing 160 mg/kg of dietary Cu and Zn. Experiment 2 was designed as a 3x2 factorial arrangement of treatments, with two mineral forms (Bioplex® and Sulphate) and three inclusion levels (Low, Medium and High). The “low” levels aimed at providing 25 mg/kg of Cu and 40 mg/kg of Zn, the “medium” levels aimed at providing 80 mg/kg of both Cu and Zn, and the “high” levels aimed at providing 160 mg/kg of both Cu and Zn in the diet. Unfortunately the Medium sulphate grower diet was contaminated with excess Zn while manufacturing, which led to the exclusion of this treatment from the study. In Experiment 1, pigs fed LB (Low Bioplex®) or HS (High Sulphate) diets grew faster (P=0.014) and their carcasses were 3.5 kg heavier (P=0.020) than LS (Low Sulphate)- or HB (High Bioplex®)-fed pigs. Pigs fed LB or HS diets had lower (P=0.001) levels of Zn in plasma, a higher (P=0.029) concentration of Zn in the pancreas and a lower (P=0.020) concentration of Zn in bone than pigs fed LS or HB diets. The concentration of Cu in liver increased (P=0.017) with the concentration in the diet as did Cu and Zn levels in faeces (P<0.001) without any difference between mineral forms. Feed conversion ratio (FCR) tended to be improved (P=0.062) by the inclusion of Bioplex® in the diet. The inclusion of Bioplex® reduced (P=0.003) subcutaneous fat depth at the P2 site by 2.2 mm compared to the sulphate. In Experiment 2, there was no difference (P>0.05) in growth rate between experimental diets, but again there was an overall improvement (P=0.012) in FCR when Bioplex® were included. Blood and tissue Cu and Zn concentrations were within normal physiological ranges in all treatments, supporting a reduction of Cu and Zn levels in the diet. Only Zn level in plasma during the growing phase and Cu and Zn concentration in tissues increased (P<0.001) with the addition in the diet. None of the biomarkers of Cu or Zn status analysed in the pigs showed any difference between the inorganic and the Bioplex® forms. Copper and Zn concentrations in faecal material decreased (P<0.001) with their inclusion in the diet, and only in the finishing collection there was a further decrease of 10% in Zn faecal concentration when Bioplex® was included instead of the sulphate at similar low levels. Carcass and meat quality measures were independent of the Cu and Zn form or level, however a higher proportion of carcasses from LB-fed pigs had <14 mm subcutaneous fat depth at the P2 site. The inclusion of Bioplex® failed to have a significant effect on Cu excretion and its inclusion had an inconsistent effect on Zn excretion. The overall findings from this thesis partially supported the hypothesis that the inclusion of Bioplex® would reduce the concentration of Cu and Zn in faeces compared to the inclusion of inorganic forms at similar inclusion levels. Nevertheless, total Cu and Zn levels in growing/finishing pig diets could be reduced from 160 mg/kg of both Cu and Zn to 30 mg/kg Cu and 60 mg/kg Zn, in either the sulphate or the Bioplex® form, without negatively affecting performance or mineral homeostasis in the pigs and significantly reducing Cu and Zn excretion (between 50 and 80%). The advantage of including Bioplex® instead of sulphates was in the improvement in FCR. Carcass and meat quality were independent of the form and level of dietary Cu and Zn.

Made available in DSpace on 2014-08-20T14:37:50Z (GMT). No. of bitstreams: 1 tese_elizabeth_schwegler.pdf: 1198143 bytes, checksum: 306f08a6253b951c8751a8eba9c7194c (MD5) Previous issue date: 2012-08-15 / The peripartum in dairy cows (three weeks before and three weeks after calving) is characterized by large changes in physiological demands in the animal where management practices, particularly nutrition, strongly influences the incidence of peripartum disorders and subsequent milk production. Most of the studies in that period in dairy cows are focused on confined systems where milk production is high. Therefore, the aim of this study was to assess metabolic markers associated with the occurrence of clinical and subclinical mastitis and insulin resistance in dairy cows in semi extensive system. Our study was divided into two major experiments with the following hypothesis: 1) medium milk production primiparous cows in semi extensive system have predictive metabolic markers of clinical and subclinical mastitis in the prepartum, 2) medium milk production pluriparous dairy cows with low rate of glucose metabolism during the prepartum, which is an indicative of insulin resistance, have higher minerals excretion in the postpartum period. In experiment 1, blood concentrations of NEFA in the prepartum period were higher, in contrast, phosphorus and glucose were lower (P <0.05) in animals with clinical mastitis postpartum. In experiment 2, pluriparous dairy cows with low rate of glucose metabolism in the prepartum had higher urinary calcium excretion in both prepartum and postpartum periods, and also the highest NEFA concentration in the prepartum period (P <0.05). The blood concentrations of calcium in dairy cows with high rate of glucose metabolism in the postpartum was elevated from the prepartum period and remained in the postpartum (P <0.05). Dairy cows kept in semi extensive system with moderate production level had predictive markers of mastitis in the prepartum, as previously demonstrated by other authors in more intensified systems of higher requirements for the animal. The highlighted marker was NEFA, however, in the second study it was shown in higher concentrations in the pluriparous dairy cows with low rate of glucose metabolism at prepartum, emphasizing the importance of this marker also in the insulin resistance. / O periparto nas vacas leiteiras (três semanas anteriores e as três posteriores ao parto) é caracterizado por grandes mudanças nas demandas fisiológicas do animal, sendo que, as práticas de manejo, principalmente nutricionais, influenciam intensamente a incidência de desordens no periparto e a subsequente produção de leite. A maioria dos estudos neste período na vaca leiteira é em sistemas confinados de alta produção leiteira, por essa razão o objetivo desta tese foi identificar marcadores metabólicos preditivos com a ocorrência de mastite clínica e subclínica e com a excreção de minerais em vacas leiteiras em sistema semi-extensivo. Nosso estudo foi estratificado em dois trabalhos com as seguintes hipóteses: 1) vacas leiteiras primíparas de média produção em sistema semi-extensivo possuem marcadores metabólicos preditivos de mastite clínica e subclínica no pré-parto; 2) vacas leiteiras pluríparas de média produção com menor taxa de metabolização de glicose, que é um indicativo de resistência da insulina, no pré-parto possuem maior excreção de minerais no pós-parto. No experimento 1 as concentrações sanguíneas de NEFA no pré-parto foram maiores e de fósforo e glicose menores (P<0,05), em animais com mastite clínica no pós-parto. No experimento 2 as vacas leiteiras pluríparas com menor taxa de metabolização de glicose no pré-parto apresentaram maior excreção urinária do cálcio no pré e pós-parto, e ainda, o NEFA mais alto no pré-parto (P<0,05). As concentrações sanguíneas de cálcio em vacas leiteiras com maior taxa de metabolização de glicose no pós-parto foi elevada desde o pré parto, mantendo-se no pós (P<0,05). Nas condições estudadas, em vacas leiteiras mantidas em sistema semi-extensivo de mediana produção foi observado que há marcadores preditivos de mastite já no pré-parto, como previamente comprovado por outros autores em sistemas mais intensificados de maiores exigências para o animal. O marcador em destaque foi o NEFA, sendo que o mesmo no segundo estudo se apresentou de forma mais elevada nas vacas leiteiras pluríparas com menor taxa de metabolização de glicose no pré-parto, enfatizando a importância deste marcador também na resistência à insulina.