Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 8 de 8
Mais filtros

Intervalo de ano de publicação
J Anim Sci ; 99(9)2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34468760


The main objective of this study was to evaluate the effect of peripartal administration of a commercially available nonspecific immune stimulant (mycobacterium cell wall fraction; MCWF [Amplimune, NovaVive Inc., Napanee, ON, Canada]) on the incidence of disease during early lactation and subsequent fertility of dairy cows. A second objective was to characterize the dynamics of circulating white blood cells (WBC) and metabolic markers following treatment administration. Cows in an United States Department of Agriculture (USDA) organic-certified dairy herd were blocked by parity and, based on sequential calving dates, randomly assigned to receive two injections (5 mL s.c.) of either a placebo (saline solution) as a control (CON; n = 71) or MCWF (n = 65) at enrollment (7 d before expected calving) and within 24 h after calving. Blood samples were collected from a subsample of the study population (MCWF = 16; CON = 18) for WBC count at enrollment, at day 2 post enrollment, and at days 1, 3, 7, and 14 after calving. Serum fatty acids, beta-hydroxybutyrate, and Ca concentrations were determined at days 1 and 7 postpartum (MCWF = 21; CON = 21). Main outcome variables included incidence risk of peripartal and early lactation health disorders and pregnancy at first artificial insemination (AI), at 100, and at 150 days in milk (DIM). In addition, the average daily milk yield up to 90 DIM and death and live culling before 305 DIM were compared. Treatment effects were assessed using multivariable logistic regression, time-to-event analyses, and repeated measures analysis of variance (ANOVA). A treatment effect on the incidence risk of some of the health disorders in the study was established. Incidence risk of metritis and clinical mastitis <28 DIM was smaller in MCWF than in CON cows (36.9% vs. 50.7% and 6.3% vs. 19.7%, respectively). On the contrary, the incidence risk of respiratory disease <28 DIM was smaller in CON (0%) than in MCWF (7.7%). Reproductive performance of multiparous cows was affected by MCWF administration: pregnancy at first AI and pregnancy at 100 and 150 DIM were greater in MCWF than in CON (35.6% vs. 19.2%; 51.1% vs. 25.0%; and 64.4% vs. 40.4%, respectively). Overall, median intervals from calving to pregnancy were 90 vs. 121 d in MCWF and CON cows, respectively. No treatment effects on the dynamics of circulating WBC or in postpartum metabolic status were established. No differences for milk yield or for the proportion of cows that survived up to 305 DIM were determined, although cows in MCWF left the herd earlier than cows in CON. In conclusion, incidence risks of metritis and mastitis in early lactation were smaller in cows receiving MCWF, whereas the incidence risk of respiratory disease was smaller in CON. Fertility significantly improved in MCWF compared with CON cows. As this study was performed in an organic-certified dairy, specific health and reproductive management practices may affect the external validity of the current findings.

Doenças dos Bovinos , Mycobacterium , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Parede Celular , Feminino , Fertilidade , Lactação , Leite , Período Pós-Parto , Gravidez , Reprodução
BMC Vet Res ; 17(1): 178, 2021 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-33926466


BACKGROUND: Hypocalcemia has detrimental effects on health and performance of dairy cows. As hypocalcemic cows show reduced feed intake, we hypothesized that cows with reduced combined rumination and eating time (CRET) may benefit from Ca supplementation. The objective was to evaluate the effect of postpartum oral Ca administration on metabolic status (Calcium [Ca], fatty acids [FA], and ß-Hydroxybutyrate [BHB] serum concentrations) and incidence of puerperal metritis (PM) in dairy cows with reduced postpartum CRET. Cows in an organic-certified dairy, diagnosed with reduced CRET (< 489 min/d; n = 88) during the first day postpartum were assigned into 1 of 2 treatments: i) Calcium administration (CA; n = 45) that received 1 Ca oral capsule (Bovikalc bolus, Boehringer Ingelheim, St. Joseph, MO) containing CaCl2 and CaSO4 (43 g of Ca) once per day, for 3 consecutive days, starting at d 1 postpartum; and ii) Control (CON; n = 43) that did not receive oral Ca. A convenience group consisting of cows with CRET ≥489 min/d was used for comparison and did not receive oral Ca (NOR; n = 96). RESULTS: At day 1 postpartum cows with reduced CRET had lower Ca serum concentrations (CA = 2.08 mmol/L; CON = 2.06 mmol/L) compared with NOR cows (2.17 mmol/L). Calcium concentrations at d 3, 5, and 12 postpartum were not different among the three groups. Serum FA concentrations at d 1, 3 and 5 postpartum were higher in both CA and CON cows compared with NOR. At d 12, only CA cows had higher FA concentrations than NOR cows. Serum BHB concentrations at d 3 were highest in CA, with no difference between CON and NOR. At d 5, BHB concentrations were higher in CA, followed by CON, and NOR. No effect was observed for Ca administration on incidence of PM and reproductive performance. CON cows had lower survival at 30 DIM (86.5%) than NOR cows (97.9%). CONCLUSIONS: The use of remote sensor technology identified cows with reduced rumination and eating time that had lower postpartum serum concentrations of calcium and altered metabolic status. However, oral calcium administration to cows with reduced CRET did not affect incidence of metabolic disorders nor reproductive health and subsequent pregnancy. Although survival at 30 days postpartum was lower for non-Ca supplemented cows, the identification of effective interventions in cows with reduced CRET requires further consideration.

Cálcio/administração & dosagem , Doenças dos Bovinos/dietoterapia , Doenças dos Bovinos/metabolismo , Período Pós-Parto/metabolismo , Ácido 3-Hidroxibutírico/sangue , Animais , Cálcio/sangue , Bovinos , Indústria de Laticínios , Suplementos Nutricionais , Endometrite/veterinária , Ácidos Graxos/sangue , Comportamento Alimentar , Feminino , Gravidez , Ruminação Digestiva
Front Vet Sci ; 7: 523, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33134329


Sensor technologies allow ethologists to continuously monitor the behaviors of large numbers of animals over extended periods of time. This creates new opportunities to study livestock behavior in commercial settings, but also new methodological challenges. Densely sampled behavioral data from large heterogeneous groups can contain a range of complex patterns and stochastic structures that may be difficult to visualize using conventional exploratory data analysis techniques. The goal of this research was to assess the efficacy of unsupervised machine learning tools in recovering complex behavioral patterns from such datasets to better inform subsequent statistical modeling. This methodological case study was carried out using records on milking order, or the sequence in which cows arrange themselves as they enter the milking parlor. Data was collected over a 6-month period from a closed group of 200 mixed-parity Holstein cattle on an organic dairy. Cows at the front and rear of the queue proved more consistent in their entry position than animals at the center of the queue, a systematic pattern of heterogeneity more clearly visualized using entropy estimates, a scale and distribution-free alternative to variance robust to outliers. Dimension reduction techniques were then used to visualize relationships between cows. No evidence of social cohesion was recovered, but Diffusion Map embeddings proved more adept than PCA at revealing the underlying linear geometry of this data. Median parlor entry positions from the pre- and post-pasture subperiods were highly correlated (R = 0.91), suggesting a surprising degree of temporal stationarity. Data Mechanics visualizations, however, revealed heterogeneous non-stationary among subgroups of animals in the center of the group and herd-level temporal outliers. A repeated measures model recovered inconsistent evidence of a relationships between entry position and cow attributes. Mutual conditional entropy tests, a permutation-based approach to assessing bivariate correlations robust to non-independence, confirmed a significant but non-linear association with peak milk yield, but revealed the age effect to be potentially confounded by health status. Finally, queueing records were related back to behaviors recorded via ear tag accelerometers using linear models and mutual conditional entropy tests. Both approaches recovered consistent evidence of differences in home pen behaviors across subsections of the queue.

BMC Vet Res ; 15(1): 450, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31829187


BACKGROUND: Negative energy balance during the transition period is a concern for both conventional and certified organic dairy systems. During early lactation, supplemental strategies are used to cope with nutrient deficiencies that are associated with impaired health, production, and reproduction. As organic certified dairies in the United States face restricted access to dietary supplements, the evaluation of products especially formulated for organic production is needed. Our objective was to assess the effect of supplementing 0.45 kg/d of an organic rumen-protected fat (RPF) on health, metabolic status, and productive and reproductive performance of organic certified Holstein cows from 1 to 150 days in milk (DIM). Two-hundred and two cows were enrolled in a randomized blocked controlled trial conducted from January to July 2017 in a certified organic dairy located in Northern Colorado (USA). Two groups were randomly assigned to be individually supplemented with organic RPF (ORG; n = 100) or control pellets (CON; n = 102) once per day, in addition to the total mixed ration (TMR). Outcomes of interest included milk yield (kg/d) and milk components, serum concentration of glucose, and non-esterified fatty acids (NEFA), resumption of cyclicity, time-to-first artificial insemination (AI), conception at first AI, and conception within 150 DIM, disease occurrence, culling, mortality. RESULTS: A significant effect for the inclusion of RPF was found in daily milk yield; RPF supplemented cows had greater milk yield (1.6 kg/d) compared to CON cows up to 150 DIM (P = 0.03). During grazing, multiparous (MP) ORG cows had greater milk yield compared to MP CON cows, whereas no effect was found in primiparous (PP) cows. Health outcomes, serum metabolite concentrations, and reproductive performance were not affected by the inclusion of RPF. Body condition loss was smaller in the ORG group up to 80 DIM; however, there was no effect on body condition during the grazing season and in the overall study period. CONCLUSIONS: These results indicate that supplementation of RPF increased daily milk yield and prevented body condition loss during at 90 DIM. However, RPF supplementation did not affect health, serum metabolite concentration, milk components, and reproductive outcomes.

Ração Animal/análise , Bovinos/fisiologia , Gorduras na Dieta/administração & dosagem , Lactação/fisiologia , Fenômenos Fisiológicos da Nutrição Animal , Animais , Glicemia/análise , Bovinos/metabolismo , Indústria de Laticínios , Dieta/veterinária , Suplementos Nutricionais , Ácidos Graxos não Esterificados/sangue , Feminino , Leite , Agricultura Orgânica/métodos , Reprodução/fisiologia
BMC Vet Res ; 15(1): 284, 2019 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-31395062


BACKGROUND: Calf stress at weaning and during transition to group pens represents a concern in dairy operations. Favoring natural behaviors, such as grooming, may help on reducing this challenge. Our objective was to evaluate the effect of a mechanical grooming brush on behavior and health of recently weaned calves, after transferring from individual to group housing. Two treatment groups (control [CON, n = 81]; automated brush [AB, n = 81]) were compared enrolling Holstein heifers (94 ± 7 d old) that were monitored for 20 days. Four cohorts, considering one CON and one AB group (19-20 calves/pen/cohort) were enrolled sequentially. Each calf was weighed, clinically evaluated, and affixed with a 3-D accelerometer sensor attached to the ear at enrolment. Continuous measurements (min/h) were generated for the following behaviors: Not-active, active, highly active, eating, and ruminating. Cameras for continuous video recording were installed in each pen, and calves were weighted at the last day of the study (d 20). Behavioral data were summarized as daily averages (min/h). Data was examined using repeated measures analysis for nested factors, with day as the time unit. RESULTS: Overall, calves had their first interaction with the brush within 2.5 days with a mean (SE) of 7 (±9.6) h after being transferred to group pens. A significant effect was determined for the interaction day by treatment on the time spent not-active and eating. Average not-active time was greater in CON compared to AB (22.8 ± 0.82 min/h vs. 21.7 ± 0.82 min/h), while eating time was greater in AB compared with CON (7.01 ± 0.40 min/h vs. 6.43 ± 0.40 min/h). Treatment groups had a similar weight gain and time to the first disease. CONCLUSIONS: We concluded that the use of a mechanical brush influenced behavior, reducing not-active time, while increasing eating time. The consequences of this change in activity require further investigation.

Criação de Animais Domésticos/instrumentação , Comportamento Animal , Bovinos/fisiologia , Animais , Feminino , Asseio Animal , Abrigo para Animais , Comportamento Social
BMC Vet Res ; 15(1): 53, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30732598


BACKGROUND: The first month of life possess significant challenges for dairy calves due to high susceptibility to digestive diseases. The objective of this study was to evaluate the effect of prebiotic supplementation with stabilized rice bran (SRB) in milk on health, immunity, and performance of pre-weaned organic dairy calves. Holstein heifer calves (n = 90) were enrolled at 6 ± 1 days old and monitored for 28 days, from July to August 2017. Calves were randomly assigned to a control (CTR; n = 45) or a treatment group (SRB; n = 45). The CTR group received milk alone and the SRB group received 120 g of SRB per day in milk to achieve a 10% w/w dose of the total calories. Daily health evaluations were conducted to score health status and disease severity (healthy, slightly affected, moderately or severely sick) of calves, through integrated assessment of diarrhea, dehydration, attitude, and milk intake. Body weights and fecal IgA quantification were completed on the first and last day of the study. RESULTS: Overall, weight gain and fecal IgA concentrations were not affected by the dietary addition of SRB. The total number of calf-days classified as healthy or sick were not different between treatment groups. Similarly, the number of calf-days categorized as slightly affected, moderately sick, or severely sick did not differ between treatment groups. Time to event analyses indicated a tendency for a treatment effect in the time to the first moderate case of diarrhea (P = 0.08), as well as in the time to recovery from diarrhea (P = 0.052), favoring control calves. CONCLUSIONS: These results indicated that the dietary addition of SRB in milk did not have an effect in health, immunity or performance of pre-weaned dairy calves.

Animais Recém-Nascidos/crescimento & desenvolvimento , Bovinos/crescimento & desenvolvimento , Fibras na Dieta , Suplementos Nutricionais , Oryza , Prebióticos , Ração Animal , Animais , Diarreia/prevenção & controle , Diarreia/veterinária , Ingestão de Alimentos , Fezes/química , Imunoglobulina A/análise , Ganho de Peso
Vet Clin North Am Food Anim Pract ; 33(2): 377-387, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28579049


Animal welfare is an essential aspect of organic dairying. Consequently, adequate lameness control should be a central component of on-farm health monitoring programs. The combination of organic management practices, including grazing requirements that are combined with different types of housing, results in unique features determining the cows' feet and legs health condition. Because the use of therapeutic resources is limited, preventive management and early detection of lameness is critical in organic dairies. This article discusses the relevant aspects of prevention and treatment options of lameness disorders in organic dairy farms.

Doenças dos Bovinos/terapia , Indústria de Laticínios , Coxeadura Animal/terapia , Agricultura Orgânica , Animais , Bovinos , Feminino
Rev. latinoam. cienc. soc. niñez juv ; 15(1): 373-388, ene. 2017. tab, ilus
Artigo em Espanhol | LILACS | ID: biblio-836183


En la investigación que referimos en este artículo, nos posicionamos en el ®momento de paso¼ que las y los jóvenes estudiantes de enseñanza media de sectores pobres experimentan al concluir su trayecto educativo secundario, a partir de la reflexión en torno a los sentidos que sus dinámicas relacionales, expectativas y aspiraciones adquieren para ellas y ellos. A través de grupos de discusión, se provocó la expresión de las hablas y experiencias juveniles, que fueron interpretadas a partir del Análisis Estructural del Discurso. El interés se centró en construir y describir las unidades elementales que organizan los significados de la conversación, para comprender sus relaciones y dinámicas en una situación de interacción comunicativa.

In the study reported on in this article, the authors focus on the“moment of transition” that students from low socio–economic backgrounds navigate when theyfinish high school. The study facilitates reflection among young people regarding the dynamics oftheir relationships, expectations and aspirations and the meanings that they have given to these concepts. Through discussion groups the authors facilitated the expression of the language andexperiences of young people, which were interpreted using structural discourse analysis techniques.The interest of the researchers centered on constructing and describing the fundamental units thatorganize the meaning of their conversations in order to understand their relationships and dynamicsin a communicative interaction situation.

Na pesquisa relatada neste artigo, estamos posicionados no “intervalo de tempo” no qual jovens estudantes do ensino médio de setores pobres experimentam ao concluir seu percurso de ensino secundário, a partir da reflexão em torno aos sentidos que sua dinâmica relacional, expectativas e aspirações adquirem para eles mesmos. Através de grupos de discussão,provocou–se a expressão de conversas e experiências juvenis, que foram interpretados a partir da Análise Estrutural do Discurso. O interesse foi centrado em construir e descrever as unidades elementares que organizam os significados da conversa, para compreender suas relações e dinâmicas em situação de interação comunicativa.

Humanos , Adolescente , Chile , Ensino Fundamental e Médio