References of "Hanzen, Christian"
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See detailCaractéristiques de reproduction de la femelle trypanotolérante de race N’Dama.
Okouyi, Marcel; Kamga Waladjo, Alain; Diarra, S et al

in Revue Africaine de Santé et de Productions Animales [=RASPA] (2014), 12(1), 3-7

Knowledge about the reproductive N’Dama remain old and very general, observations have been most often performed on a limited number of animals and in different contexts. This inventory confirms the need ... [more ▼]

Knowledge about the reproductive N’Dama remain old and very general, observations have been most often performed on a limited number of animals and in different contexts. This inventory confirms the need to continue and intensify so as federated possible studies to further clarify the characteristcs and reproductive performance of this important development potential of cattle that represents the N’Dama to Africa. [less ▲]

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See detailProduction laitière et santé mammaire (Bio Ingénieurs)
Hanzen, Christian ULg

Learning material (2013)

Ce cours de 4 heures s'inscrit dans cadre du module "Production laitière par le ruminant" dispensé aux étudiants de master bio-ingénieur en sciences agronomiques. Les objectifs spécifiques ont été définis ... [more ▼]

Ce cours de 4 heures s'inscrit dans cadre du module "Production laitière par le ruminant" dispensé aux étudiants de master bio-ingénieur en sciences agronomiques. Les objectifs spécifiques ont été définis en accord avec le professeur Yves Beckers co-responsable du module. Ce cours a pour objectif général de définir la mammite, ses conséquences, ses signes d'alerte au niveau de l'individu et du troupeau, son approche diagnostique, ses facteurs de risque au niveau individuel et d'élevage et ses grandes lignes d'approche thérapeutique. [less ▲]

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See detailComprendre la mammite bovine comme une enzootie dynamique
Theron, Léonard ULg; Hanzen, Christian ULg

Article for general public (2013)

Health disorders in bovine herds are, in essence, multifactorial. They are based on the equilibrium among various factors. The major difficulty in managing endemias in livestock production emerges from ... [more ▼]

Health disorders in bovine herds are, in essence, multifactorial. They are based on the equilibrium among various factors. The major difficulty in managing endemias in livestock production emerges from two elements: the extreme variability of practices among farms and over time on one hand and on the other hand, the crossed impact of various factors producing the same result. A simple example will illustrate the two problems: Mastitis has epidemiological components that govern their own response to means of prevention. Because no two dairy farms ever have fifty per cent of their livestock production practices in common, the establishment of the usual means of prevention will never have the same dosable impact in each of the two farms (Bradley et al. 2007; Théron et al. 2009). Further, in view of the variability of certain practices or adjustments over time, a situation can vary while all other factors remain constant, due to a neglected invisible factor, thus diminishing the strength of the prevention argument. Each of us has known situations in which post-dipping did not generate the anticipated effects, and situations in which, after a transitory improvement linked to milking practices, the situation degrades again for a cause associated with the milking machine or feeding. The conclusion of this introduction is both simple and complex: the integrated control of mastitis is based on long-term monitoring. This monitoring is justified by the economic and societal impact of this disease. Good monitoring implies the definition of key measurable control points. The aim of this article will be to define the indicators and epidemiological objectives that enable the level of mammary health and its evolution to be defined over time. [less ▲]

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See detailNiveau de production et fécondité des vaches et des troupeaux laitiers wallons
Chapaux, Philippe; Glorieux, Géry; Hanzen, Christian ULg

Poster (2013, December)

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See detailTractus génital des vaches zébus (Bos indicus) au Niger.
Moussa Garba, Mahamadou; Marichatou, H; Issa, M et al

in Revue d'Elévage et de Médecine Vétérinaire des Pays Tropicaux (2013), 66(4), 137-142

The anatomical characteristics, and the ovarian and pathological structures of the genital tract of 500 zebu (Bos indicus) females belonging to four breeds (Azawak, Bororo, Djelli, Goudali) were studied ... [more ▼]

The anatomical characteristics, and the ovarian and pathological structures of the genital tract of 500 zebu (Bos indicus) females belonging to four breeds (Azawak, Bororo, Djelli, Goudali) were studied at Niamey’s slaughterhouse in Niger from August 15 to December 15, 2011. Each animal was examined before slaughter. The cows and heifers were on average 8 ± 2.5 years old. Their mean body condition score was 1.6 ± 0.6 and mean carcass weight 113 ± 21 kg. The anatomical characteristics of the genital tract did not show differences between breeds (p > 0.05). The following characteristics were observed: cervix diameter 3.4 ± 1.1 cm, cervix length 8.1 ± 2.5 cm, horn length 21.6 ± 5.2 cm, horn diameter 1.6 ± 0.5 cm, length and width of the right ovary 19.8 ± 4.4 and 11.2 ± 3.8 mm, of the left ovary 18.8 ± 4.5 and 10.2 ± 3.3 mm, and weight of the right and left ovaries 2.9 ± 1.8 and 2.5 ± 1.6 g, respectively. A corpus luteum was identified in only 14% cases and no visible follicles were found on the surface of the ovaries in 32% cases. These characteristics were significantly (p < 0.05) influenced by the age of the animal. Among the examined females, 7.4% were confirmed pregnant. Various genital tract diseases (cysts, uterine infection, free martinism, pyometra...) were observed in 10.4% of the genital tracts. [less ▲]

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See detailAnalyse de l'efficience des traitements de mammites de 50 fermes de Wallonie dans la base LAECEA
Theron, Léonard ULg; Reding, Edouard; Detilleux, Johann ULg et al

Conference (2013, October 11)

Mastitis is the most “antibiotic consuming” pathology in dairy medicine. Though antibiotics and antibiograms are known to vets since the early fifties, our practices did not evolved a lot from empiric ... [more ▼]

Mastitis is the most “antibiotic consuming” pathology in dairy medicine. Though antibiotics and antibiograms are known to vets since the early fifties, our practices did not evolved a lot from empiric antibiotic therapy. Indeed, the need for a treatment, the cost and the delay for an antibiogram are most of the time incoherent with a routine practice. Nevertheless, there is a surge for rational use of antibiotics. Our study was based on 1100 mastitis events from 30 Belgian farms collected between January 2011 and June 2012. We chose to compare tissular cure (TC) based on the threshold of 200.000 somatic cells/ml in milk at milk control at least 60 days after the clinical mastitis event. Regarding the mastitis event, severity (according 3 grades: alteration of milk as grade 1, alteration of quarter as grade 2 and alteration of general state as grade 3), quarter, treatments were recorded. We also assessed a chronicity status based on previous somatic cell count (SCC) of the cow. It was considered a new case a cow which at least 15 days before had an SCC <200.000 cells/ml, other were marked as chronic cases. In our distribution, we see a seasonal rise of incidence between January and May. This period would represent twice as many mastitis as the summer period. Overall TC reaches 46% of all mastitis events, which is quite poor. Rear quarters had significantly lower TC (p<0,05%). Grade 3 mastitis had lower TC, 42,6% (p<0.05%) versus 48,9 % for grade 2 and 44,2% for grade 1. Almost 49% of all mastitis was considered as chronic cases, which TC was 33% on average, whereas new cases reached 55,3% TC. Study of treatment was frustrating given the high number of different combinations of treatments. It was underlined that 4th generation cephalosporins (C4G) were the most used in our cohort, followed by aminopenicillin/methicillin association (PENA/PENM) and 1st generation cephalosporins/aminoglycosids (C1G/AG) association. Of these intramammary treatments, 20% of the cases were submitted to a second intramammary drug, mostly C1G or C1G/AG. One third of the cases were treated parenterally with antimicrobials, mostly macrolids, fluoroquinolones and penethacillin. Finally, 10% of mastitis was treated with anti-inflammatory drugs, mostly tolfenamic acid and flunixin-meglumin. Comparing mastitis without use of a secondary intramammary drug, only PENA and C1G/AG reached more than 60% TC. Considering new cases, then C1G/AG, PENA/PENM and Prednisolone containing specialties were above 60% TC. Use of a parenteral injections increased TC only on new cases (+12%), but not on chronic cases. Refining by severity, TC improved with a parenteral on new cases, mainly in grade 1 (+20%). Regarding associated factors, TC was negatively affected by chronicity, parity and lactation stage. Indeed, TC was lower on cases from more than 4 month in milk, third lactation (OR = 2.8 for no cure) compared with previous, and chronic cases (OR=2,6). Seemingly, chronicity was positively associated with parity and season. The 3rd parity cases had higher chances to be chronic ones (OR = 1,7), as well as cases from April to September (OR = 1,6). This evaluation of cure is rather simple and has a good variability which allows several questions about the real match between antimicrobial treatment for mastitis and the udder inflammation. Based on our epidemiological data, we can modify routine management of mastitis, as some cases might not worth the antimicrobial treatment. [less ▲]

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See detailImpact des périodes d'attente et de reproduction sur la fécondité de la vache laitière
Chapaux, Philippe; Glorieux, Géry; Hanzen, Christian ULg

in Wallonie Elevages (2013)

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See detailNegative effect of milk production level on reproduction performances. Not a fatality.
Hanzen, Christian ULg; Glorieux, Géry; Chapaux, Philippe

Poster (2013, September)

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See detailAnalyse des pratiques de détection des chaleurs dans les élevages bovins laitiers algériens.
Yahimi, Abdelkrim; Djellata, N; Hanzen, Christian ULg et al

in Revue d'Elévage et de Médecine Vétérinaire des Pays Tropicaux (2013), 66(1), 31-35

Methods used to detect estrus were analyzed in 222 cattle farms, spread over five wilayas center (Tizi Ouzou, Blida, Medea, Tipaza and Bouira) in Algeria. The questionnaire contained general information’s ... [more ▼]

Methods used to detect estrus were analyzed in 222 cattle farms, spread over five wilayas center (Tizi Ouzou, Blida, Medea, Tipaza and Bouira) in Algeria. The questionnaire contained general information’s related to livestock (number of females, stall, and specialisation) but also the methods of heat detection (periods of observation signs considered as important) and any complementary tool used. The majority of farmers (57%) were facing a problem of heat detection. In only 49% of cases, they inseminated their cows for the first time 50 to 90 days after calving. A breeder in two (53%) detected oestrus twice a day and 40% observed three times a day. Observations took place whenever suitable in the day. They declared that a cow was in oestrus primarily on the presence of a vulvar discharge (19%) or mount acceptance (16%). Herd size or specialisation had no impact on the frequency of signs considered. Cows not detected in estrus during the first 60 days after calving were subjected to a clinical examination by a veterinarian in76% of farms. Some helps to the detection such as (rotating schedule, pencil mark) were used by 34% of farms. These practices are influenced (factors responsible for the manifestation, times and number of observation, anestrus post-partum and aids detections of heat) or no (signs of heat, waiting period and difficulty of detection) by speculation and herd size. [less ▲]

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See detailHAEMATOLOGICAL PROFILES OF CALVES BELONGING TO HERDS WITH BOVINE NEONATAL PANCYTOPENIA HISTORY IN AND AROUND WALLONIA (BELGIUM).
Ronzoni, Anna ULg; Theron, Léonard ULg; Bayrou, Calixte ULg et al

in Buiatrissima, 8th ECBHM Symposium, 28-30 August 2013, Bern, Proceedings (2013, August)

The objective of the present study was to verify the hypothesis of subclinical BNP cases, by random sampling and haematological analysis in different herds with BNP history, in order to obtain a better ... [more ▼]

The objective of the present study was to verify the hypothesis of subclinical BNP cases, by random sampling and haematological analysis in different herds with BNP history, in order to obtain a better epidemiological picture of this disease. [less ▲]

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See detailGetting insights on bovine mastitis treatment efficacy based on tissular indicators with an integrated udder health management file: Project LAECEA.
Theron, Léonard ULg; Reding, Edouard; Rao, Anne-Sophie ULg et al

Poster (2013, August)

Mastitis is the most “antibiotic consuming” pathology in dairy medicine. Though antibiotics and antibiograms are known to vets since the early fifties, our practices did not evolved a lot from empiric ... [more ▼]

Mastitis is the most “antibiotic consuming” pathology in dairy medicine. Though antibiotics and antibiograms are known to vets since the early fifties, our practices did not evolved a lot from empiric antibiotic therapy. Indeed, the need for a treatment, the cost and the delay for an antibiogram are most of the time incoherent with a routine practice. Nevertheless, there is a surge for rational use of antibiotics. Our study was based on 1100 mastitis events from 30 Belgian farms collected between January 2011 and June 2012. We chose to compare tissular cure (TC) based on the threshold of 200.000 somatic cells/ml in milk at milk control at least 60 days after the clinical mastitis event. Regarding the mastitis event, severity (according 3 grades: alteration of milk as grade 1, alteration of quarter as grade 2 and alteration of general state as grade 3), quarter, treatments were recorded. We also assessed a chronicity status based on previous somatic cell count (SCC) of the cow. It was considered a new case a cow which at least 15 days before had an SCC <200.000 cells/ml, other were marked as chronic cases. In our distribution, we see a seasonal rise of incidence between January and May. This period would represent twice as many mastitis as the summer period. Overall TC reaches 46% of all mastitis events, which is quite poor. Rear quarters had significantly lower TC (p<0,05%). Grade 3 mastitis had lower TC, 42,6% (p<0.05%) versus 48,9 % for grade 2 and 44,2% for grade 1. Almost 49% of all mastitis was considered as chronic cases, which TC was 33% on average, whereas new cases reached 55,3% TC. Study of treatment was frustrating given the high number of different combinations of treatments. It was underlined that 4th generation cephalosporins (C4G) were the most used in our cohort, followed by aminopenicillin/methicillin association (PENA/PENM) and 1st generation cephalosporins/aminoglycosids (C1G/AG) association. Of these intramammary treatments, 20% of the cases were submitted to a second intramammary drug, mostly C1G or C1G/AG. One third of the cases were treated parenterally with antimicrobials, mostly macrolids, fluoroquinolones and penethacillin. Finally, 10% of mastitis was treated with anti-inflammatory drugs, mostly tolfenamic acid and flunixin-meglumin. Comparing mastitis without use of a secondary intramammary drug, only PENA and C1G/AG reached more than 60% TC. Considering new cases, then C1G/AG, PENA/PENM and Prednisolone containing specialties were above 60% TC. Use of a parenteral injections increased TC only on new cases (+12%), but not on chronic cases. Refining by severity, TC improved with a parenteral on new cases, mainly in grade 1 (+20%). Regarding associated factors, TC was negatively affected by chronicity, parity and lactation stage. Indeed, TC was lower on cases from more than 4 month in milk, third lactation (OR = 2.8 for no cure) compared with previous, and chronic cases (OR=2,6). Seemingly, chronicity was positively associated with parity and season. The 3rd parity cases had higher chances to be chronic ones (OR = 1,7), as well as cases from April to September (OR = 1,6). This evaluation of cure is rather simple and has a good variability which allows several questions about the real match between antimicrobial treatment for mastitis and the udder inflammation. Based on our epidemiological data, we can modify routine management of mastitis, as some cases might not worth the antimicrobial treatment. [less ▲]

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See detailInvestigation of biological markers to evaluate the adaptation of the newborn Belgian Blue calf to the extrauterine life. A pilot study.
Ronzoni, Anna ULg; Theron, Léonard ULg; De Marchin, Emmanuelle et al

in Dalin, Göran (Ed.) 15th International Conference on Production Diseases in Farms Animals, Book of Abstracts (2013, June)

Adaptation to extrauterine life and immunity transfer at calving are more at stake when dealing with highly productive breeds such as the Belgian Blue Cattle Breed (BBCB). The purpose of the present pilot ... [more ▼]

Adaptation to extrauterine life and immunity transfer at calving are more at stake when dealing with highly productive breeds such as the Belgian Blue Cattle Breed (BBCB). The purpose of the present pilot study was to evaluate different blood markers, from the birth to the first week of life in BBCB calves, in order to investigate fundamental aspects of the adaptation to the extrauterine life as passive immunity transfer and early energy metabolism. Eighty calves coming from 10 different farms located in Wallonia (Belgium) were enrolled. A clinical examination was performed to verify viability and maturity at birth. Blood samples were collected at birth, day 1 and day 3 to 7. Passive immunity transfer analysis included serum and colostrum immunoglobulin G (IgG) concentration, and plasmatic selenium concentration (Se). Glycemia, serum insulin and cortisol concentration have been considered for the energy metabolism analysis. The data collected were statistically analysed using logistic regression and unpaired t-test. All calves were born alive, viable and mature by caesarean section. Mortality rate was 0% at one week and 5% at three months. Only 33% of calves had an IgG concentration >16g/L after one week of age, while only 34% of colostra had an IgG concentration >70g/L. Glycemia and serum insulin concentration at birth were significantly lower than other breeds, and plasmatic selenium concentration were coherent with low supplemented dams. We compared calves across IgG concentration classes (>16 g/L vs <16g/L). The crosssectional analysis of the risk of FPT when given low IgG concentration colostra has shown a non significant odd ratio (OR 1,058 and 0,39116 g/L) (p<0,001). No significant difference has been shown between cortisol and glycemia (p=0,3) nor insulin and glycemia (p=0,2) at birth. These data suggest a significant difference in BBCB calves on several metabolic markers, but they also revealed that immunity transfer and micronutrition of pregnant hyper-productive dams remain a challenge in modern farms. [less ▲]

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See detailFécondité des vaches et troupeaux laitiers wallons. Effet du management.
Chapaux, Philippe; Glorieux, Géry; Hanzen, Christian ULg

in Wallonie Elevages (2013), 4

L’intervalle moyen entre vêlages est de 409 jours. Pour les 25 % meilleurs troupeaux (3125 annéesz troupeaux) et vaches (107.700 lactations), il est respectivement de 387 et 346 jours. L’objectif ... [more ▼]

L’intervalle moyen entre vêlages est de 409 jours. Pour les 25 % meilleurs troupeaux (3125 annéesz troupeaux) et vaches (107.700 lactations), il est respectivement de 387 et 346 jours. L’objectif classiquement proposé d’un veau par vache et par an n’est atteint que dans 0,38% des troupeaux et par une vache sur quatre (27%). L’augmentation de la production laitière moyenne s’accompagne d’un allongement de l’intervalle entre vêlages. Des performances de reproduction comprises entre 380 jours pour les élevages dont la production est inférieure à 8000 kg et de 390 jours pour les élevages dont la production est supérieure à 8000 kg de lait sont néanmoins tout à fait possibles. L’impact de l’augmentation du niveau de production sur l’allongement de l’intervalle entre vêlages est limité. Les éleveurs dont les troupeaux ont des moyennes de production égales ou supérieures à 8.000 kg tirent un meilleur parti de l’environnement (effet positif) que ceux dont les troupeaux ont des moyennes de production inférieures à 7.000 Kg. La marge brute par vache augmente avec le niveau de production laitière moyen du troupeau. [less ▲]

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See detailMammites suraigues : Quel diagnostic différentiel, Quels germes peuvent jouer un rôle?
Theron, Léonard ULg; Hanzen, Christian ULg

Conference given outside the academic context (2013)

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See detailTarir nos vaches laitières en 2013 : Comprendre, Depister, Prévenir
Theron, Léonard ULg; Hanzen, Christian ULg

Conference given outside the academic context (2013)

Tarir ses vaches laitières hautes productrices de nos jours demeure un défi, de part le niveau de production, les pathologies puerpérales liées, et la compréhension de la dynamique d’infection au ... [more ▼]

Tarir ses vaches laitières hautes productrices de nos jours demeure un défi, de part le niveau de production, les pathologies puerpérales liées, et la compréhension de la dynamique d’infection au tarissement. Au travers d'exercices choisi, d'analyse des données d'élevage, les participants seront amenés à décrire la situation d'élevage, et les facteurs de risque investiguables par le praticien. [less ▲]

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See detailApplications de l’échographie à la reproduction des ruminants
Hanzen, Christian ULg

Learning material (2013)

Cette présentatiion illustre les prerequis physiques et anatomiques nécessaires à la compréhension des champs d'application de l'échographie en reproduction bovine.

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See detailStructural esuation models to estimate risk infection and tolerance to bovine mastitis
Detilleux, Johann ULg; Theron, Léonard ULg; Duprez, Jean-Noël ULg et al

in Genetics, Selection, Evolution (2013), 45

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See detailExamen ante et postmortem du tractus génital de vaches laitières du Sud Vietnam.
Nguyen Kien, Cuong; Hanzen, Christian ULg

in Revue d'Elévage et de Médecine Vétérinaire des Pays Tropicaux (2013), 66(3), 85-90

De février à août 2012, 507 vaches de réforme, de race croisée Holstein x Lai Sind, d’âge moyen 8,5 ans, ont été examinées ante-mortem (détermination de l’âge par l’examen de la denture, évaluation du ... [more ▼]

De février à août 2012, 507 vaches de réforme, de race croisée Holstein x Lai Sind, d’âge moyen 8,5 ans, ont été examinées ante-mortem (détermination de l’âge par l’examen de la denture, évaluation du score corporel, examen vaginal au moyen d’un spéculum) et post-mortem (examen échographique des ovaires, examen du contenu utérin). Près de la moitié (44,4 %) avaient un score corporel inférieur à 2,5. Les fréquences du pneumovagin et de l’urovagin étaient respectivement de 33,1 % et 14,7%. L'âge et le score corporel ont exercé un effet significatif sur la fréquence de ces affections. Les fréquences des écoulements vaginaux et des contenus utérins anormaux étaient respectivement de 12,1% et 5,4%. Sur les 507 vaches examinées, 226 vaches (44,6%) étaient en anœstrus. Parmi les anœstrus, les fréquences des anœstrus pathologiques fonctionnels (types 0, I et II), associés à un kyste, à un pyomètre ou à une gestation ont été respectivement de 37,3%, 2 %, 0,4 % et 4,9 %. Les anœstrus pathologiques de type 0 et I ont été plus fréquemment observés chez les vaches maigres et chez celles qui étaient âgées de moins de 6 ans. [less ▲]

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