1,721,002 research outputs found
Genetic and nongenetic variation of milk processing characteristics in Irish and Italian dairy cattle
Full text linkMilk processing characteristics describe the aptitude of milk to be transformed into different dairy products. Milk intended for cheese production should coagulate early in order to generate a strong curd; cheesemaking is favored by low milk pH, small casein micelle, and high content of minerals such as Ca, P, and Mg. Small casein micelle, high milk pH, and low inorganic Ca2+ favor the stability of milk protein to heat treatments, which is a fundamental characteristic for the production of dried milk. The quantification of such milk quality traits is important at the dairy industry level in order to define more precisely the best use of milk prior to processing. The overall objectives of the present thesis were: i) to develop mid-infrared spectroscopy (MIRS) prediction models for a fast and on-line measurement of milk processing characteristics; ii) to study the effect of stage of lactation, parity, breed, heterosis and recombination loss on a large number of predicted processing phenotypes; and iii) to estimate (co)variance components of milk technological aspects in order to potentially breed for improved milk processability.
The effectiveness of MIRS as a fast and cost-effective technique to predict rennet coagulation time, curd-firming time, curd firmness at 30 and 60 min after rennet addition (milk coagulation properties), heat coagulation time, casein micelle size, pH and minerals (Ca, K, Mg, Na, and P) was evaluated. The proportion of variance explained by the prediction models in external validation ranged from 13% (casein micelle size) to about 70% (minerals, with the exception of Na, and pH).
Factors associated with the phenotypic variation of MIRS-predicted milk coagulation properties, heat coagulation time, casein micelle size, and pH, and minerals was evaluated on large spectral datasets. Milk coagulation properties were more favorable (i.e., short rennet coagulation time and strong curd firmness) for cheese manufacturing in early lactation, concurrent with the lowest values of both pH and casein micelle size, and the greatest milk mineral content; milk was more stable to heat in mid-lactation. Milk yielded by primiparae was more adapted for both cheese and milk powder production. Jersey cows, on average, yielded milk more suitable for cheese rather than milk powder production. Simmental cows produced milk with the greatest content of Ca and Na, and milk of Holstein-Friesian had the lowest P content. Genetic parameters for milk processing characteristics were studied. Heritability estimates ranged from 0.16 (heat coagulation time) to 0.54 (Ca). Within-trait genetic correlations were weaker than 0.40 only at the peripheries of the lactation. On average, more than 80% of the additive genetic variation in each trait was associated with the height of the lactation profile for all traits. Milk processing traits were generally antagonistically correlated with milk production suggesting that emphasis should be placed to milk processability to halt any deterioration.Le qualità tecnologiche del latte descrivono l’attitudine di questa materia prima ad essere trasformata in prodotti lattiero-caseari. Il latte destinato alla produzione di formaggio dovrebbe coagulare in tempi relativamente brevi e generare un coagulo consistente; in quest’ambito la coagulazione del latte è favorita da valori bassi di pH ed alta acidità titolabile, micelle caseiniche piccole e alto contenuto di minerali come Ca, P e Mg. Micelle caseiniche piccole, valori di pH alti e un basso contenuto di Ca2+ favoriscono la stabilità del latte a trattamenti termici, una caratteristica fondamentale per la produzione di latte in polvere. La determinazione delle caratteristiche tecnologiche del latte è un aspetto rilevante nell’industria lattiero-casearia al fine di definire in maniera più efficiente la destinazione e l’utilizzo dello stesso durante la trasformazione. Gli obiettivi generali della presente tesi sono: i) sviluppare modelli di predizione utilizzando la spettroscopia nel medio-infrarosso (MIRS) per la determinazione routinaria di caratteri tecnologici del latte; ii) studiare l’effetto di stadio di lattazione, ordine di parto, razza, eterosi e ricombinazione su un elevato numero di fenotipi predetti; iii) stimare le componenti di (co)varianza degli aspetti tecnologici del latte al fine di verificare la possibilità di migliorarli geneticamente.
È stata valutata l’efficacia del MIRS quale tecnica rapida e relativamente economica per predire il tempo di coagulazione, il tempo di rassodamento e la consistenza del coagulo a 30 e 60 minuti dall’aggiunta del caglio (proprietà coagulative del latte), la stabilità al calore, la dimensione delle micelle caseiniche, il pH e i minerali (Ca, K, Mg, Na e P). La proporzione di varianza spiegata dai modelli di predizione in validazione esterna varia dal 13% per la dimensione delle micelle caseiniche a circa il 70% per i minerali (con l’eccezione di Na e pH).
I fattori associati alla variazione fenotipica delle predizioni MIRS delle proprietà coagulative del latte, della stabilità al calore, della dimensione delle micelle caseiniche, del pH e del contenuto di minerali sono stati valutati utilizzando dataset di spettri di popolazione. Le proprietà coagulative del latte sono più favorevoli (breve tempo di coagulazione e elevata consistenza del coagulo) per la produzione di formaggio all’inizio della lattazione, contestualmente a valori bassi di pH e della dimensione delle micelle caseiniche, e ad alte concentrazioni di minerali; la stabilità risulta più elevata a metà lattazione. Il latte prodotto da bovine primipare è maggiormente adatto alla produzione sia di formaggio sia di latte in polvere. Soggetti di razza Pezzata Rossa producono un latte con i più alti contenuti di Ca e Na, mentre il latte di Frisona ha i valori più bassi di P.
Infine, sono stati determinati i parametri genetici per i caratteri tecnologici menzionati in precedenza. Le stime di ereditabilità variano da 0.16 (stabilità al calore) a 0.54 (Ca). Le correlazioni genetiche entro carattere sono inferiori a 0.40 solamente ad inizio e fine lattazione. In media, più dell’80% della varianza genetico-additiva risulta associata con l’altezza del profilo di lattazione di tutti i caratteri studiati. In generale, i caratteri tecnologici del latte sono correlati antagonisticamente con la produzione di latte. Alla luce dei risultati si ritiene opportuna una concreta applicazione di tali caratteri negli attuali programmi di miglioramento genetico
Milk mineral variation of Italian dairy cattle breeds predicted by mid-infrared spectroscopy
No full textConsumer’s quality perception has changed in the last years and healthy aspects are becoming more and more relevant. Cow milk is an important source of minerals, especially Ca, K, Mg, Na, and P. Large-scale monitoring of milk mineral content is difficult due to expensive and time-consuming reference analyses, and therefore phenotyping of these traits at the population level is hardly achievable. Aim of the present study was to investigate sources of variation of milk Ca, K, Mg, Na, and P, predicted by mid-infrared spectroscopy models developed after uninformative variables elimination, on a large multi-breed spectral dataset (n=123,240). Cattle breeds considered were Holstein-Friesian, Brown Swiss, Alpine Grey, and Simmental. Sources of variation were studied using mixed models, including the fixed effects of breed, month and year of sampling, days in milk, parity, and the interactions between the main effects. Random factors were herd nested within breed, cow nested within breed, and the residual. All fixed effects were highly significant (P<0.01) in explaining the variation of milk mineral concentration. Milk of Simmental cows exhibited the greatest concentration of minerals. Alpine Grey breed had greater concentration of Ca and P compared to HF. These aspects could be important for a valorization of local breeds. Variation of concentration of Ca, Mg, Na, and P across lactation was significant and it exhibited an opposite trend to that of milk yield, with the lowest values around the peak of lactation. On the contrary, K concentration resembled the trend of milk yield
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Total antioxidant activity of bovine milk: Phenotypic variation and predictive ability of mid-infrared spectroscopy
No full textThe phenotypic variation of milk total antioxidant activity (TAA) and the ability of mid-infrared spectroscopy to predict this novel trait was investigated. Total antioxidant activity was measured through the reference spectrophotometric method on 1249 individual milk samples of Holstein Friesian cows. Sources of variation of milk TAA were investigated using a mixed model, which included the fixed effects of days in milk, parity and calving season, and the random effects of herd-test-date and error. Mid-infrared spectroscopy prediction models were developed using partial least squares regression approach. The average level of milk TAA was 6.93 mmoL L-1 of Trolox equivalents; this exhibited a coefficient of variation of 15% and showed weak phenotypic correlations with milk quality traits. Values of TAA were lower in early lactation than in late lactation. Mid-infrared spectroscopy prediction models reached a coefficient of determination in external validation of 0.41, suggesting that they are not adequate for analytical purposes
Study of fertility traits in Italian Jersey Cattle
Full text linkSelection Index of Italian Jersey cattle is composed by breeding values (BVs) of production traits, type traits and somatic cell score. Knowing selection for milk yield has been proved to deteriorate fertility performances, aim of the Italian Holstein, Brown and Jersey Breeders Association (ANAFIBJ) is to develop a fertility index inspired to the model they use for Italian Holstein breed. The model used considers different phenotypes for heifer and cow evaluation, but while for Holstein only the first three parities are considered, for Jersey all parities are considered to overcome the lower size of the population. Starting from two different datasets, containing data on inseminations and lactations we derived several fertility traits. From the inseminations dataset we harvested information on the dates of services, which we grouped in baches of a maximum length of 300 days. The groups of inseminations have then been attached to the calvings happened in an interval of 260–300 days from at least one of the services in the group. Phenotypes estimated for both heifers and cows are Non-Return Rate at 56 days (NRR56) and Interval from First to Last service (IFL); Age at First Insemination (AFI) has been computed only for heifers, while Days from delivery To First Service (DTFS) and Equivalent Milk Yield 305 (EMY305) only for cows. The values of the phenotypes have been filtered to be in line with biological and economic criteria of cattle farming. The final dataset is composed of 35081 records for heifers and 100285 records for cows. Correlations and Co-Variances between the phenotypes have been calculated. For Heifers we observe a slight positive correlation between AFI and NRR56 (ρxy = −0.061) and a negative correlation between NRR56 and IFL (ρxy = −0.349); IFL and AFI are negatively correlated (ρxy = −0.048). For cow fertility traits NRR56 resulted to be positively correlated with DTFS (ρxy = 0.088) and negatively correlated with EMY305 (ρxy = −0.092) and IFL (ρxy = −0.293); DTFS resulted negatively correlated to IFL (ρxy = −0.015) and EMY305 (ρxy = −0.045), while IFL and EMY305 resulted positively correlated (ρxy = 0.083). The next step is to calculate genetic parameters and EBVs for fertility traits for Italian Jersey
Predictive ability of mid-infrared spectroscopy for major mineral composition and coagulation traits of bovine milk by using the uninformative variable selection algorithm
Full text linkMilk minerals and coagulation properties are important for both consumers and processors, and they can aid in increasing milk added value. However, large-scale monitoring of these traits is hampered by expensive and time-consuming reference analyses. The objective of the present study was to develop prediction models for major mineral contents (Ca, K, Mg, Na, and P) and milk coagulation properties (MCP: rennet coagulation time, curd-firming time, and curd firmness) using mid-infrared spectroscopy. Individual milk samples (n = 923) of Holstein-Friesian, Brown Swiss, Alpine Grey, and Simmental cows were collected from single-breed herds between January and December 2014. Reference analysis for the determination of both mineral contents and MCP was undertaken with standardized methods. For each milk sample, the mid-infrared spectrum in the range from 900 to 5,000 cm−1 was stored. Prediction models were calibrated using partial least squares regression coupled with a wavenumber selection technique called uninformative variable elimination, to improve model accuracy, and validated both internally and externally. The average reduction of wavenumbers used in partial least squares regression was 80%, which was accompanied by an average increment of 20% of the explained variance in external validation. The proportion of explained variance in external validation was about 70% for P, K, Ca, and Mg, and it was lower (40%) for Na. Milk coagulation properties prediction models explained between 54% (rennet coagulation time) and 56% (curd-firming time) of the total variance in external validation. The ratio of standard deviation of each trait to the respective root mean square error of prediction, which is an indicator of the predictive ability of an equation, suggested that the developed models might be effective for screening and collection of milk minerals and coagulation properties at the population level. Although prediction equations were not accurate enough to be proposed for analytic purposes, mid-infrared spectroscopy predictions could be evaluated as phenotypic information to genetically improve milk minerals and MCP on a large scale
Effectiveness of mid-infrared spectroscopy to predict bovine milk minerals
No full textThe importance of milk mineral composition for human health is well known and accepted. Because of that, a rapid and cost effective monitoring of milk mineral composition is an important goal to achieve. This study aimed to investigate the potential of mid-infrared spectroscopy to predict calcium, potassium, sodium, magnesium and phosphorus in milk through the use of Uninformative Variables Elimination partial least squares (UVE-PLS) procedure. Individual samples (n=246) of Holstein-Friesian, Brown Swiss, Simmental and Alpine Grey cows from different stages of lactation and parities were collected from single-breed herds. Reference analysis was undertaken with inductively coupled plasma optical emission spectrometry (ICP-OES) in accordance with standardized methods. For each milk sample MIRS analysis in the range of 900 to 5,000 cm-1 was performed. Prediction models were developed using PLS regression after UVE for each considered trait and prediction accuracy was based on leave one out cross validation (246 segments). The coefficient of determination in cross validation was greatest for phosphorus (0.72), followed by potassium (0.70), calcium (0.68) and magnesium (0.67). Sodium prediction was poor, with a very low coefficient of determination (0.46). All the prediction models were unbiased (P<0.05). The ratio of performance deviation suggested that prediction models for P can be used for analytical purposes. Calcium and potassium exhibited RPD close to the threshold and thus they could be considered for analytical purposes as well. Results from the present study demonstrated that MIRS, combined with PLS regression is useful for the acquirement of milk mineral phenotypes at population level and the use of UVE combined with PLS represent a valid approach to improve the accuracy of prediction models
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Effect of morphological characteristics and productive traits on the survival of dual-purpose Simmental cows
Full text linkIn recent years, dairy farmers have observed a substantial decrease in cow survival, with a direct negative consequence on the profitability. Shorter lifespan raises questions about animal welfare and farming conditions at which cows are exposed to. Traditionally, the cows’ productive life length is affected by voluntary and involuntary culling, e.g. sale, slaughter, salvage, or death. Culling risks are affected by animal-related features such as calving events, lactation stage, energy balance, reproduction, and aging, but also external factors, namely management and season. The present study aimed to investigate the morphological and productive traits affecting the survival of Italian Simmental dual-purpose cattle. Data available belonged to 2656 Italian Simmental dairy cows from 324 dairy herds (Emilia Romagna region, Italy). Cows involved in the study were linear classified once, as primiparous, between the 2002/2003 to 2019/2020 dairy seasons. Kaplan-Meier survival analyses were performed with the LIFETEST procedure of SAS software v 9.4 using milk yield, muscularity, and body condition score (in classes) as independent variable and survival at the subsequent lactation up to the 6th as dependent variable. As expected, the culling risk increased with parity, i.e. as the age of cows progressed. In general, animals with a low production level and medium body conditions have the highest probability of survival compared to high-producing cows. This trend was more evident in later parities: in fact, cows in parity 5 with low milk production and medium muscularity were more likely (+20.11% of probability) to survive at the subsequent lactation compared to others (13.99 vs 10.49, for medium and high production levels, respectively). Moreover, high-producing cows with medium body conditions were those with the lowest probability to survive at the subsequent lactation. The reasons that could explain these findings may be linked to the metabolic stress experienced by the cows during lactation. Indeed, especially during the peripartum period, lactating cows undergo a state of negative energy balance and a reduction of immune competence. Results from this study indicated that other than productivity level, morphological traits are important for making culling decisions in the Italian Simmental cattle
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