Chilean Dairy Research Articles

Association between disease occurrence and fertility of dairy cows in three geographic regions of Chile

The objective was to analyze the association between disease occurrence during early lactation and reproductive performance and survival of dairy cows in high-producing herds, under different management practices in three geographic regions of Chile. Data included 30,757 lactation records of cows calving from January 2013 to June 2014 in three different locations: Central (C) area (n = 6198 cows in eight herds), Central-South (CS) area(n = 17,234 cows in 12 herds), and South (S) area (n = 7325 cows in six herds). Data were analyzed using logistic regression and ANOVA, considering cow as the experimental unit. Covariables offered to the models included parity number, season of calving, cow and herd relative milk yield, geographic location, and management system. Average milk yield (305 ME) per cow were 12,091, 11,783, and 6852 kg for C, CS, and S regions, respectively. Time from calving to first service and time to conception were consistently greater for cows with at least one disease event within 50 days in milk (DIM), for cows that were reported lame, or for cows that had mastitis or metritis. The odds (95% confidence interval) of pregnancy at 150 DIM (P150) and the odds of survival until 150 DIM (S150) for cows that had at least one disease event within 50 DIM were 0.84 (0.79–0.91) times the odds of pregnancy and 0.25 (0.22–0.28) times the odds of survival for healthy cows. The odds of P150 for cows located in the C and CS areas were 1.56 (1.36–1.80) and 1.16 (1.04–1.30) times the odds of P150 for cows in the S area. The odds of S150 for cows located in the C and CS areas were 0.48 (0.37–0.62) and 0.54 (0.42–0.67) times the odds of S150 for cows in the S area. These data suggested that cow health status and geographic location are significantly associated with reproductive performance and survival in this population of Chilean dairy cows.

Single nucleotide polymorphisms in immunity-related genes and their association with mastitis in Chilean dairy cattle

Mastitis remains a major cattle disease with great global economic implications. Various approaches are currently employed in attempts to improve understanding of mastitis resistance and develop phenotypic markers for use in breeding programs (e.g., somatic cell score), including QTL discovery, wide-genome association studies, and identification of candidate genes related to immune function. This study evaluated three single nucleotide polymorphisms contained in Toll-like receptor 4 (TLR4) and lactoferrin (LF) genes associated with mastitis traits: TLR4 P-226, TLR4 2021, and LF P-28. Genotyping was performed by restriction fragment length polymorphism-polymerase chain reaction (PCR) and high-resolution melting quantitative PCR from genomic DNA of four dairy cattle breeds (Holstein, Jersey, Montbeliarde, and Overo Colorado) previously classified as healthy, with clinical or with subclinical mastitis. The high-resolution melting quantitative PCR allowed genotyping of each locus and resulted in allele frequencies indicating that all loci were in Hardy-Weinberg equilibrium. The TT genotype of TLR4 2021 was significantly associated with the healthy condition, but no associations with somatic cell score were evident. Further studies are therefore necessary in order to confirm the results of this investigation.

Concentración de selenio en leche de estanques de rebaños lecheros del sur de Chile y su relación con indicadores productivos

An observational study was conducted in 59 Chilean dairy farms to evaluate bulk tank milk selenium (Se) concentration, and its association with measures of m...

Factors related to the level of occurrence of bovine abortion in Chilean dairy herds

The objectives of this study were (1) to estimate the frequency and dynamics of bovine abortion syndrome; (2) to identify groups of cows affected by abortion; and (3) to assess the characteristics of herd management and lactation associated with abortion rates. The study was performed using farmers’ historical records for 77 dairy herds in the south of Chile (Bio-Bio, Los Lagos and Los Ríos Regions) collected between 2001 and 2005. These records included 44,959 lactations from 20,977 cows. In addition, farm management practices were assessed through a questionnaire involving 127 herds. The herds were selected according to the farmers’ willingness to participate and the existence of high-quality electronic records assessed by the practitioners advising the farms. The frequency distribution of observed, inferred and general abortions was estimated by the incidence rate (IR). A hierarchical logistic regression analysis with random intercept was performed to assess the association between herd management and lactation characteristics and the occurrence of abortion. An IR of 1.74 per 100 cow-months at risk was estimated. General abortions were highest in first-parity cows (IR: 1.85 per 100 cow-months at risk). Abortion cases inferred from individual records were most frequent in the first trimester of gestation and decreased over time, whereas observed abortions increased in accordance with gestation time. The period of highest risk for abortion was around 82 days of gestation. Management practices such as a tap drinking system for cows, a closed herd, vaccination against leptospirosis, exclusive use of pasture for cows, animal density, the time that a calf stays with its dam and breed type were associated with the risk of abortion.The results of this study demonstrate that there is a large underestimation of abortion rates when only farmers’ abortion records are analysed, and there are several factors associated with the risk of abortion.

From import dependency to export orientation the case of the chilean dairy sector

Iberoamericana – Revista Nórdica de Estudios de Latinoamérica y el Caribe, es una revista académica arbitrada, interdisciplinaria y bilingüe. Es administrada por el Instituto de Estudios Latinoamericanos de la Universidad de Estocolmo en colaboración con otras universidades nórdicas con el objetivo de presentar investigación de alta calidad sobre América Latina.La revista publica artículos originales enfocados en temas relacionados con las ciencias sociales y humanidades. Investigadores de todo el mundo son bienvenidos a enviar sus manuscritos en inglés o español.

A retrospective study on the association between different lengths of the dry period and subclinical mastitis, milk yield, reproductive performance, and culling in Chilean dairy cows

The objective of this study was to determine the association between different dry period lengths and somatic cell counts, milk yield, reproductive performance, and risk of early culling during the subsequent lactation of Chilean dairy cows. The length of the dry period was classified into 5 categories: 0 to 30 d, 31 to 52 d, 53 to 76 d, 77 to 142 d, and 143 to 250 d. Generalized mixed models were used and included herd as random effect. Time-to-event analyses were performed for evaluation of reproductive performance and culling risk. The odds of subclinical mastitis (log linear score, LNSCC ≥ 4.5) during early lactation increased with extended dry periods (143 to 250 d) during first, second, and third test day compared with the reference dry period of 53 to 76 d [odds ratio (OR)=1.27, 1.16, and 1.31, respectively]. Short (0 to 30 d) and extended dry periods had a detrimental effect on early lactation and 305-d milk yield compared with the reference dry period. Longer dry periods were associated with increased number of days for calving-to-first service interval and calving to conception interval. Average calving-to-first service interval for short and extended dry period were 83 d and 89.4 d, respectively. Average days to conception were 127.8 d and 131.4 d for a dry period of 31 to 52 d and extended dry period, respectively. Similarly, the number of services per conception increased with length of previous dry period from 1.62 (31 to 52 d) to 2.44 (143 to 250 d). Cows with previous short and extended dry period had higher odds of culling when compared with cows in the reference group (OR=2.20 and 1.57, respectively). Compared with the reference group, cows in the dry period category 77 to 142 d had the highest odds of death followed by the category 143 to 250 d (OR=1.27 and 1.18, respectively).When death and live culling were combined, the highest odds of combined death and culling were for cows in the categories 0 to 30 d and 143 to 250 d (OR=1.63 and 1.44, respectively). We conclude that extended dry periods (143 to 250 d) increase the odds of subclinical mastitis occurrence during early lactation and have a negative association with reproductive performance. Short and extended dry periods were negatively associated with early lactation and 305-d milk yield and were related to increased overall culling when compared with the reference dry period.

Associations between lesion-specific lameness and the milk yield of 1,635 dairy cows from seven herds in the Xth region of Chile and implications for management of lame dairy cows worldwide

AbstractLameness is one of the greatest infringements of welfare in dairy cows. The objective of this study was to investigate associations between milk yield and foot lesions causing lameness in Chilean dairy cattle with the hypothesis that if we can demonstrate that lameness reduces yield, and so income, from lame dairy cows then we have both economic and welfare arguments for reducing lameness in dairy cattle. For one year, all lame cows from seven farms with Holstein Friesian cattle were treated by their herdsmen. Herdsmen were trained by the researcher and a colour atlas was utilised to assist in diagnosis of lesions. All abnormalities on the foot and the suspected cause of lameness were recorded, and cattle were treated. A two-level hierarchical model with repeated monthly test-day yields within cows was used to investigate the impact of double sole (DS), sole ulcer (SU), white line disease (WLD), digital dermatitis (DD) and all ‘other’ causes of lameness on milk yield before and after treatment. There were 1,635 cows with complete data. Cattle with a DS were higher yielding than cattle that were never lame with a reduction in yield from four months before treatment. Cattle lame with DD were higher yielding than non-lame cattle before and after treatment. For all causes of lameness, yield increased the month after treatment. We conclude that lesions causing lameness reduced the milk yield of dairy cows in these seven herds in Chile. We discuss the current evidence base for prevention of lameness in dairy cows and hypothesise that rapid treatment is a feasible current approach to improve cow welfare immediately and probably reduce milk lost; more evidence for effective prevention is required.

Patrones temporales de recuento de células somáticas, grasa, proteína y nitrógeno ureico en leche de estanque y su asociación con fertilidad en ganado lechero en la zona centro-sur de Chile

The objective of this study was to describe and evaluate the dynamics of bulk tank (LE) somatic cell counts (RCS), milk urea nitrogen (NUL), fat (%) and protein (%) and to analyze their association with reproductive indexes, considering monthly LE samples from 187 farms (-12, 000 dairy cows at any time) in Central-Southern Chilean dairy cattle from 1997 to 2007. Reproductive indexes included in the study were calving to first service interval (IPPS, d), calving to conception interval (IPP, d) and services per conception (SC). Bulk tank LNRCS was positively associated with herd size, milk yield (305 mature equivalent), milk solids and NUL. Bulk tank NUL was positively associated with milk yield and LE RCS. Average calving to first service interval was 92.5 d and showed a positive association with LE protein percentage and NUL. Average calving to conception interval was 138.9 d and was positively associated with LE NUL. It is concluded that the most significant changes in LE components during the last 10 years, in Central-Southern Chilean Holstein cattle, corresponded to a decrease in RCS and an increase in NUL. Changes in RCS reflect an improvement in mammary health, milk quality and milk yield. Bulk tank NUL concentrations were high during the last 5 years in study and depended on factors such as milk production, protein percentage, month and year. Bulk tank NUL was the milk component with the most notorious association with reproductive parameters. More data about protein nutrition should be evaluated in this Chilean cattle population.

Effect of High Somatic Cell Counts on Reproductive Performance of Chilean Dairy Cattle

Mastitis is caused by environmental or contagious bacteria related to poor milking procedures or hygiene, and continues as an economically important disease. Clinical mastitis may affect the interestrus interval and cause abortion by stimulating the release of inflammatory mediators and pyrexia. Subclinical mastitis results in lower reproductive performance, and a negative effect of a linear somatic cell count on embryo survival has been reported. Still, a paucity of research exists on the magnitude of the effect of subclinical mastitis on reproductive performance of lactating dairy cows. The hypothesis was that subclinical mastitis, diagnosed by an elevated somatic cell count (SCC), affects fertility and reproductive performance of dairy cattle by a reduction in conception and an increase on the risk of abortion. The objectives were to evaluate the effect of high SCC during early lactation on reproductive performance, and to determine the association between a high linear SCC (LNSCC) and the risk of abortion in a population of central-southern Chilean dairy cattle.

Fonterra in Latin America: a Case Study of a New Zealand Company Abroad

This article looks at Fonterra’s investments into the Latin American dairy industry. It traces the development of the New Zealand co-operative from exporter of New Zealand dairy products to investor into other countries. It explains why Latin America is a particular focus of this expansion, and outlines the Dairy Partners America alliance with NestlÉ. The article narrates the controversies and achievements of Fonterra’s involvement in Chile, the site of most investment, before considering how New Zealand involvement affects the development of the Chilean dairy industry.

Effect of high somatic cell counts on reproductive performance of Chilean dairy cattle

The objectives were to evaluate the effect of high linear somatic cell counts (LNSCC ≥4.5) during early lactation on reproductive performance and to estimate their association with the risk of abortion in a population of central-southern Chilean dairy cattle. The analysis included records from a population of 157 farms and considered 1,127,405 test-day records including 101,944 lactations that began between 1997 and 2006. After data edits, the analyses of calving to first service and calving to conception intervals consisted of 88,633 and 70,877 lactations, respectively. Once controlling for significant variables, time to first breeding was 21.8 d longer in cows with at least 1 high LNSCC before the first breeding compared with controls. Cows with at least 1 high LNSCC before the fertile breeding had an increment in time to conception of 48.7 d and required, on average, 0.49 more services to conceive. The odds of conception at first service in cows with a high LNSCC within 30 d before [after] breeding were 0.85 (0.81 to 0.89; 95% confidence interval) [0.82 (0.78 to 0.87; 95% confidence interval)] times the odds of conception for cows without a high LNSCC during that period. The Cox proportional hazard model indicated that after correction by calving year, lactation number, and milk yield standardized to 305 d, the risk of pregnancy decreased by 44% if a high LNSCC occurred before breeding. Cows registering a high LNSCC during the first 90 d of gestation had an increased risk of abortion, being 1.22 (1.07 to 1.35; 95% confidence interval) times more likely to abort than nonaffected cows. It is concluded that subclinical mastitis, measured as LNSCC ≥4.5, had a significant effect on reproductive performance in Chilean dairy cattle.

Evaluation of Four Commercial Enzyme-Linked Immunosorbent Assays for the Diagnosis of Bovine Paratuberculosis in Chilean Dairy Herds

The accuracy of 4 commercial enzyme-linked immunosorbent assays (ELISAs) for diagnosis of bovine paratuberculosis was compared using sera from 53 Mycobacterium avium subsp. paratuberculosis (MAP) fecal culture-positive dairy cows (cases) and sera from 345 dairy cattle resident in 11 fecal culture-negative herds on 2 consecutive occasions 1 year apart (controls). The specificity of all 4 ELISA kits was >99%, and their diagnostic sensitivity ranged from 30.2% to 41.5%. Pairwise comparison of ELISAs found no significant differences (McNemar's chi-square test > 0.05), and assay agreement for categorical assay interpretation (positive or negative) was high (>98%) with kappa values ranging from 0.84 to 0.95. Receiver operating characteristic (ROC) curve analysis and the corresponding area under the ROC curves indicate that kit B had the highest overall accuracy. Thus, all 4 ELISA kits for bovine paratuberculosis had comparable accuracy when tested on Chilean dairy cattle, with kit B having a slight statistical advantage based on ROC area under the curve analysis. This suggests that any of the 4 kits could be appropriate for herd certification and for paratuberculosis control programs on Chilean dairy cattle.

Diagnostic validity and costs of pooled fecal samples and individual blood or fecal samples to determine the cow- and herd-status for Mycobacterium avium subsp. paratuberculosis

Two tests are used on a regular basis to detect Mycobacterium avium subsp. paratuberculosis ( Map): ELISA and fecal culture. Fecal culture is considered more sensitive and specific but is costly and requires 3–4 months for results. Pooling of fecal samples of individual animals may reduce the high costs of fecal culture. The objective of the study was to investigate the diagnostic validity and costs for pooling of fecal samples in dairy farms relative to culture or an ELISA on individual samples to determine the cow- or herd-status for Map. Fifty fecal and blood samples per herd were collected in 12 Chilean dairy herds. The sensitivity of pooling was estimated given the pool-size, amount of shedding in the pool and the prevalence in the herd. The sensitivity of the pools relative to individual fecal culture was 46% (95% CI 29–63%) and 48% (28–68%) for pools of 5 and 10 cows, respectively. The sensitivity of the pools was lower in pools with low shedders (26 and 24% for pools of 5 and 10, respectively) than in pools with moderate or heavy shedders (>75% sensitivity). Pools of 10 cows are the better option to determine or monitor the herd status. A whole-herd ELISA is the least expensive way to determine the status of individual cows but has a lower Se and Sp than individual culture.

Diagnosis of Paratuberculosis by Fecal Culture and ELISA on Milk and Serum Samples in Two Types of Chilean Dairy Goat Herds

Fecal culture has been the primary method used to diagnose paratuberculosis in goats. It is laborious, slow, and expensive. Validation of enzyme-linked immunosorbent assays (ELISAs) on milk samples could make paratuberculosis testing more widely available for goat farmers. The aim of this study was to determine the accuracy of serum and milk ELISAs for paratuberculosis, relative to fecal culture, in Chilean dairy goats. Eight dairy goat herds were selected. Feces, blood, and milk samples were collected from all female goats >2 years old. Fecal samples were cultured using Herrold egg yolk medium with mycobactin J and antibiotics. Serum and milk samples were tested using a commercial ELISA kit for Mycobacterium avium subsp. paratuberculosis antibody detection. A total of 383 goats were tested by ELISA and fecal culture. The sensitivity of ELISA on serum and milk relative to fecal culture was 74.3% (95% CI: 59.8-88.8) and 60% (95% CI: 43.8-76.2), respectively. The corresponding values for ELISA specificity based on the percentage of non- M. avium subsp. paratuberculosis-infected goats testing ELISA-negative were 98.6% (95% CI: 96.6-100) and 99.3% (95% CI: 97.9-100) on serum and milk, respectively. Proportions of positive results for serum and fecal samples were significantly different, whereas the proportions of positive results for milk and fecal samples were not significantly different. The milk ELISA had a moderate level of agreement with fecal culture results (Kappa = 0.57). The paratuberculosis ELISA on goat milk samples may be a cost-effective, accurate alternative to fecal culture.

Milking Machines on Chilean Dairy Farms and their Effects on Somatic Cell Count and Milk Yield: A Fied Study

espanolSe evaluaron treinta y cuatro lecherias de la zona centro sur de Chile para describir el funcionamiento de las maquinas de ordeno con respecto al vacio, pulsadores, lineas de leche y caracteristicas de las pezoneras y su relacion con el recuento de celulas somaticas (SCC) y la produccion de leche (MY). Un nivel de vacio inadecuado (NVL) influyo negativamente en el SCC. El aumento de SCC fue mas acentuado en maquinas de ordeno con lineas altas que con lineas medias y bajas. MY tambien fue influida negativamente por un alto NVL inadecuado. Mayores niveles de MY fueron encontrados en lecherias que tenian 0.05) en MY. No hubo influencia del tipo de pulsacion en SCC y MY, pero en todos casos la asociacion pulsacion-pulsador produjo un SCC sobre las recomendaciones internacionales. Una correlacion positiva altamente significativa entre la altura de la linea de leche y SCC fue encontrado (r = 0.41; P EnglishThirty-four dairy farms in the south central zone of Chile were evaluated in order to describe the functioning of the milking machines with respect to vacuum, pulsators, milklines and cluster characteristics and their relationship with somatic cell count (SCC) and milk yield (MY). An inadequate nominal vacuum level (NVL) was one factor that influenced negatively SCC. The increase of SCC was more accentuated in those milking machines with high-lines than mid- and low-lines. MY was also negatively influenced by an inadequate high NVL. Higher MY value was found in those farms which had 0.05) on MY. There was no influence of the pulsation type on SCC and MY, but in all cases the association pulsation-pulsator produced an SCC above international recommendations. A highly significant positive correlation between milkline height and SCC was found (r = 0.41; P

Genetic parameters and trends in the Chilean multibreed dairy cattle population.

Estimates of additive and nonadditive multibreed co-variance components, genetic parameters, and predicted genetic values for first lactation 305-d mature equivalent (ME) milk yield, fat yield, and protein yield were computed using data from a sample of 3316 cows from the Chilean Holstein-other breeds multibreed population. Variances and covariances were estimated by 2-trait REML analyses using a Generalized Expectation-Maximization algorithm applied to multibreed populations. Multiple estimates of additive genetic, nonadditive genetic, and environmental variances from 2-trait analyses were averaged to yield a single variance estimate for each trait and effect. Heritabilities were moderate for all traits in Holstein, other, and Holstein x other crossbred groups. Interbreed interactibilities (ratio of nonadditive genetic to phenotypic variances) were all near zero. Multibreed additive, nonadditive, and total genetic trends were estimated using the complete dataset (56,277 cows). Upward trends between 1990 and 2000 existed for all traits, genetic effects, and breed groups, except for 305-d ME protein yield in 1/4 Holstein, indicating that Chilean dairy producers were successful in choosing progressively better semen and sires from imported and local sources over time.

Herd-level ELISA seroprevalence of bovine viral diarrhea antibodies in bulk-tank milk in Chilean dairy herds

Our objective in this cross-sectional study was to determine the seroprevalence in 1996 of commercial dairy herds in central Chile positive to bovine viral diarrhea (BVD) virus, by the detection of antibodies in bulk-tank milk samples. Samples were obtained from 501 dairy farms (∼50,000 cows) from the Metropolitan, VI, VII and VIII regions of Chile. An indirect ELISA was used to detect BVD antibodies. An absorbance ( A 450)≥0.55 was considered positive. The apparent proportion of positive herds ranged from 71.2 to 83% by region and did not differ by region. We concluded that exposure to BVD was widely distributed in the central area of Chile in 1996.

Structural change in the chilean dairy sector: export potential and challenges.

During the decade of the nineties, the Chilean dairy sector showed great competitive capacity as shown by high growth rates in production and substantial quality improvements of primary inputs, and by an important modification in production seasonality. Although Chile has traditionally been an importer of milk, starting in 1993, production started to increase at higher rates than domestic consumption. This has lead to a significant rise of exports and a gradual reduction in the quantity of imports. The only way to sustain constant rises in milk production in an environment of slow domestic demand growth is with access to international markets. Prices paid to producers and production costs are among the world`s lowest, which, together with potential improvements to productivity and efficiency, gives the Chilean dairy sector an export potential. The realization of this potential requires a number of decisions to improve productive efficiency at both the primary and industrial level, and a better coordination among the different levels of the marketing chain.En la decada de los 90 el sector lechero chileno mostro una gran capacidad competitiva, manifestada en altas tasas de crecimiento de la produccion, en un mejoramiento substancial de la calidad de la materia prima, y en una modificacion importante de la estacionalidad de la produccion. Si bien Chile ha sido tradicionalmente un pais importador de leche, a partir de 1993 la produccion comienza a crecer a mayores tasas que el consumo domestico, por lo cual se observa un crecimiento significativo en las exportaciones y una disminucion paulatina en la importaciones. La unica manera de sostener un crecimiento constante en la produccion, en un contexto de lento crecimiento de la demanda domestica, es accediendo a los mercados internacionales. Por otra parte, los precios pagados a productor y los costos de produccion de leche en Chile se ubican entre los menores del mundo, lo que, unido al potencial de mejoramiento en la productividad y eficiencia, permiten sostener que Chile tiene un potencial exportador significativo. Para ello se requiere de un conjunto de acciones para mejorar la eficiencia productiva a nivel primario e industrial, y una mejor coordinacion entre todos los sectores involucrados.

Farm- and host-level risk factors for papillomatous digital dermatitis in Chilean dairy cattle

A cross-sectional study was conducted in southern Chile between January and March, 1996, to identify risk factors for papillomatous digital dermatitis (PDD) in lactating dairy and dual-purpose cows. A total of 3,265 cows from 22 farms were examined in the milking parlor for PDD lesions. Additional information was collected from dairies' computerized records and by direct interview of managers. Data were analyzed using logistic and logistic-binomial regression (with dairy as a random-effect term). German Red-Pied (dual-purpose) cows were significantly ( P < 0.05) less likely (odds ratio (OR) = 0.3) to have PDD lesions than German Black-Pied and Holstein crossbreds. First-parity cows had the highest odds of PDD, and odds diminished, in a dose-effect manner, as parity increased. Odds of PDD increased with increasing days in lactation. Cows that calved during winter were more likely to have PDD (OR = 1.4) than those calving at any other season. Cows on farms that bought heifers in the past 10 years had a 3-fold increase in the odds of PDD compared to those on farms that never bought heifers. Loose-housed cows had a higher risk of PDD (OR = 7), followed by cows in free stalls or in open corrals (OR = 2.8 and 1.3, respectively), compared to cows on pasture all year. Cows on dairies that used a footbath during 1996 were less likely (OR = 0.3) to have PDD than those in dairies not using one. Parlor type was associated with PDD, but this was likely an effect of parlor design on ease of inspection of cows' feet. A policy of trimming all cows' vs. only lame cows' feet and a policy about buying adult cows did not have significant effects on PDD risk.