Modeling rennet coagulation time and curd firmness of milk.

Abstract Milk coagulation properties (MCP) are traditionally expressed using rennet coagulation time (RCT), time to curd firmness (CF) of 20mm (k 20 ), and CF 30min after enzyme addition (a 30 ) values, all of which are single-point measures taken from the output of computerized renneting meters, such as the Formagraph. Thus, traditional MCP use only some of the available information. Moreover, because of the worldwide spreading of breeds such as the Holstein-Friesian, characterized by late-coagulating milk, it happens often that some samples do not coagulate at all, that a 30 is strongly and negatively related to RCT, and that k 20 is not measurable. The aim of the present work was to model CF as a function of time (CF t , mm) over a 30-min interval. The model tested was C F t = C F P × 1 − e − k C F × $t − R C T$ , where CF P (mm) is the potential asymptotical CF at an infinite time, k CF (min −1 ) is the curd firming rate constant, and RCT is measured inminutes. The CF t model was initially applied to data of milk of each of 105 Brown Swiss cows from 7 herds, each sampled once (trial 1). Four samples did not coagulate within 30min. Eighty-seven of the 101 individual equations obtained fit the CF data of milk samples very well, even though the samples differed in composition, and were produced by cows of different ages and days in milk, reared on different farms (coefficient of determination >0.99; average residual standard deviation=0.21mm). Samples with a very late RCT (slowly coagulating samples) yielded so few observational data points that curve parameters could not be precisely estimated. The repeatability of CF t equation parameters was estimated using data obtained from 5 replicates of each of 2 samples of bulk milk from 5 Holstein-Friesian cows analyzed every day for 5 consecutive days (trial 2). Repeatability of RCT was better than that of the other 2 parameters. Moreover, traditional MCP values (RCT, a 30 , and k 20 ) can be obtained from the individual CF t equations, using all available information. The MCP estimated from equations were very similar to the single-point measures yielded by the computerized renneting meter (coefficient of determination >0.97), but repeatability was slightly better. The model allowed the estimation of k 20 for samples with a very late coagulation or with very slow curd firming. Finally, the 3 novel parameters used to assess different milk samples were less interdependent than are the traditional measures, and their practical and scientific utility requires further study

Effect of Finnsheep crossbreeding on Lamon sheep performance: in vivo traits

The objective of this trial was the comparison of the in vivo traits of Lamon (L), a local meat breed of the Eastern Italia Alps, and Finnsheep X Lamon (F x L) fattening lambs. Forty-one lambs (25 L and 16 F x L) of both sexes were weaned at 8 weeks of age and fattened for 14 weeks. The diet (11,6 MJ/kg d.m.M.E.) consisted of maize silage ad lib., 200 g/d of dried sugar beet pulp, 150 g/d of soybean meal and 30 g/d supplement. F x L lambs grew slightly more than L lambs (197 vs 176 g/d; P .1) while M.E. requirements for growth, estimated assuming a maintenance requirement of.44 MJ • d-1 • kg-1 • L.W.-75, resulted higher (+7 %) for F x L than for L lambs (2.18 vs 2.04 MJ • kgDG • kg-1 • L.W.-75; P < .1). The ram-lambs showed superior growth potential and feed efficiency in respect to the ewe-lambs. In conclusion it appears that crossbreeding with Finnsheep is not detrimental to the in vivo performance of fattening Lamon lambs except for a slight increase of the energy requirements for growth

double muscled and conventional cattle have the same net energy requirements if these are related to mature and current body protein mass and to gain composition

The hypothesis tested in this paper is that double-muscled (DBM) and conventional cattle, considerably differing in body composition, have similar NE requirements when: a) NE(m) is scaled as a function of current (P(i)) and adult (P(m)) protein mass; and b) ME for gain (ME(g)) is estimated from protein (Pr) and lipid (Lr) retention and their partial ME use efficiencies, the k(p) and k(l) values, respectively. First, 2 databases were examined: 1 was developed combining well known literature information from comparative slaughter trials conducted on British beef steers; the other was based on a trial conducted using extremely lean DBM Piemontese bulls. From the first database, NE(m) was calculated to be 1.625 × P(i) ÷ P(m) × P(m)(0.73) (MJ/kg(0.73)). From the second database, the daily ME(g) was determined as 22.8 MJ × Pr ÷ k(p) + 38.74 MJ × Lr ÷ k(l), assuming (from prior reports) that k(p) = 0.20 and k(l) = 0.75. Thereafter, ME(m) was defined as ME intake minus ME(g), and, hence, NE(m) was predicted as 1.625 × P(i) ÷ P(m) × P(m)(0.73) (where 1.625 was the value obtained from the first dataset). The resulting k(m) (NE(m)/ME(m)) averaged 0.67. This k(m) value did not differ from that (0.65; P = 0.12) predicted by Garrett's equation, which uses dietary ME content as the only predictive variable. Second, the procedure was tested for the ability to detect effects on k(m) caused by increasing BW and dietary factors not estimable from the dietary ME content only. Data were gathered from a trial involving 48 DBM Piemontese bulls divided into 4 groups fed 1 of 4 diets differing in CP content (145 or 108 g/kg DM), with or without addition of 80 g/d of rumen-protected CLA (rpCLA). Bulls were examined at 3 consecutive periods of growth, corresponding to 365, 512 and 631 kg of average BW. All energy balance items were influenced by increasing BW, except k(m) (P = 0.61), in agreement with the expectation that NE(m) requirement depends on the degree of maturity (P(i)/P(m)) and the P(m)(0.73) of an animal, whereas k(m) reflects characteristics of the feed provided. The k(m) value was also influenced by the CP × rpCLA interaction (P = 0.013). We conclude that DBM and British beef steers have similar NE requirements when these are scaled as a function of P(i) and P(m), and gain composition, considering Pr, k(p), Lr and k(l). The proposed procedure will be useful to predict the energy requirements and feed use in cattle of different types that vary in BW, provided that body and gain compositions are known or accurately predicted

Heritability estimates of enteric methane emissions predicted from fatty acid profiles, and their relationships with milk composition, cheese-yield and body size and condition

In the present study we estimated the genetic parameters of enteric methane emissions (EME) traits predicted from milk fatty acid profile (FA) and those of their predictors in 1,091 Brown Swiss cows reared on 85 farms in order to assess the potential of using EME-related phenotypes in selective breeding. Univariate and bivariate genetic models were fitted in a Bayesian framework. The means of the marginal posterior distribution of intra-herd heritability ranged from 0.12 for estimated methane production (g/d/cow) to 0.24 for estimated methane yield (g/kg dry matter intake [DMI]), with intermediate values for estimated methane intensity, increasingly higher when expressed per kg of corrected milk (0.13), fresh cheese (0.16), or cheese solids (0.20). Regarding the correlations, the milk quality traits and percentage cheese yields were generally moderately correlated with the estimated EME traits, and were variable in terms of sign. Daily milk and cheese yield traits were, as expected, all highly positively correlated with estimated daily methane production. In contrast, they were negatively correlated with estimated methane yield and intensity, the estimates being large in the case of phenotypic and herd correlations, and low in the case of additive genetic and residual correlations. With the exception of the negative correlations with daily methane production, EME traits exhibited trivial correlations with body size and BCS of cows, which, in turn, were negatively correlated with milk yield. Although the results should be validated on a larger population and different breeds, our study demonstrate the presence of additive genetic variation of EME traits, which could be exploited in breeding programmes for the improvement in both milk production and the ecological footprint of dairy farming.HighlightsEnteric methane emissions (EME) of dairy cows can be estimated on the basis of milk fatty acid profile.EME exhibited exploitable genetic variation.Genetic selection could be preferentially based on predicted methane intensity per kg of milk, or per kg of cheese in countries where milk production is used mainly for cheese-making. Enteric methane emissions (EME) of dairy cows can be estimated on the basis of milk fatty acid profile. EME exhibited exploitable genetic variation. Genetic selection could be preferentially based on predicted methane intensity per kg of milk, or per kg of cheese in countries where milk production is used mainly for cheese-making

From milk to cheese: Evolution of flavor fingerprint of milk, cream, curd, whey, ricotta, scotta, and ripened cheese obtained during summer Alpine pasture

The role of each step of cheese and ricotta making in development of flavor of cheese and other dairy products is not yet well known. The objectives of this study were to characterize volatile organic compounds (VOC) in cheese and ricotta making with bulk milk from cows grazing in a highland area and to evaluate their evolution in the various dairy products and by-products obtained during the production processes. A group of 148 cows was grazed day and night on pasture from June to September. A total of 7 cheese-making sessions were carried out using the bulk milk collected every 2 wk during summer pasturing according to the artisanal procedure used for Malga cheese production. All milks, products, and by-products were sampled, and the VOC content of milk, cream, whey, ricotta, scotta (residual liquid), fresh cheeses, and cheeses ripened for 6 and 12 mo was determined by solid-phase microextraction gas chromatography-mass spectrometry. Forty-nine compounds were identified belonging to the following chemical families: alcohols (13), aldehydes (9), esters (8), free fatty acids (6), ketones (5), lactones (2), sulfurs (2), terpenes (2), phenol (1), and benzene (1). The results showed that the amounts of VOC in the various dairy products differed significantly. Comparisons between the VOC of 4 types of milk (whole evening, skim evening, whole morning, mixed in the vat) showed that the skimming process had the greatest effect, with about half of all the VOC analyzed affected, followed by time of milking (evening milking vs. morning milking) and mixing (skim evening milk mixed with whole morning milk). In general, among fresh products, cream had higher contents of fatty acids, sulfurs, and terpene volatile compounds than fresh cheese and ricotta, whereas ricotta showed a very high VOC amount compared with fresh cheese, probably due to its high processing temperature. The effects of the progressive nutrient depletion in milk during processing were investigated by comparing the amounts of VOC in vat milk, whey, and scotta. Although milk contained greater amounts of nutrients, whey and especially scotta had higher concentrations of VOC, with the exception of esters, sulfurs, terpenes, and phenolic compounds, as a result of physicochemical and microbial modifications during processing. Finally, the effect of ripening was tested by comparing the VOC of fresh and ripened cheeses (6 and 12 mo), revealing that VOC release increased dramatically during the first semester and further with increasing the ripening period to 1 yr. In particular, some alcohols (butan-2-ol), aldehydes (2-methylpropanal, hexanal, and heptanal), esters (ethyl butanoate and ethyl hexanoate), fatty acids (acetic, butanoic, and hexanoic acids), and ketones (butan-2-one, pentan-2-one, and heptan-2-one) showed a very large increase. In conclusion, according to the artisanal milk processing carried out for Malga cheese production, the quantity of VOC was shown to increase about 3 times during cheese making (from milk in vat to fresh cheese plus whey), almost 4 times during ricotta making (from whey to ricotta plus scotta), and about 16 times during 1 yr of ripening of cheese

Invited review: Genetics and modeling of milk coagulation properties

AbstractMilk coagulation properties (MCP) are conventionally measured using computerized renneting meters, mechanical or optical devices that record curd firmness over time (CFt). The traditional MCP are rennet coagulation time (RCT, min), curd firmness (a30, mm), and curd-firming time (k20, min). The milk of different ruminant species varies in terms of CFt pattern. Milk from Holstein-Friesian and some Scandinavian cattle breeds yields higher proportions of noncoagulating samples, samples with longer RCT and lower a30, and samples for which k20 is not estimable, than does milk from Brown Swiss, Simmental, and other local Alpine breeds. The amount, proportion, and genetic variants (especially κ-casein) of milk protein fractions strongly influence MCP and explain variable proportions of the observed differences among breeds and among individuals of the same breed. In addition, other major genes have been shown to affect MCP. Individual repeatability of MCP is high, whereas any herd effect is low; thus, the improvement of MCP should be based principally on selection. Exploitable additive genetic variation in MCP exists and has been assessed using different breeds in various countries. Several models have been formulated that either handle noncoagulating samples or not. The heritability of MCP is similar to that of other milk quality traits and is higher than the heritability of milk yield. Rennet coagulation time and a30 are highly correlated, both phenotypically and genetically. This means that the use of a30 data does not add valuable information to that obtainable from RCT; both traits are genetically correlated mainly with milk acidity. Moreover, a30 is correlated with casein content. The major limitations of traditional MCP can be overcome by prolonging the observation period and by using a novel CFt modeling, which uses all available information provided by computerized renneting meters and allows the estimation of RCT, the potential asymptotic curd firmness, the curd-firming rate, and the syneresis rate. Direct measurements of RCT obtained from both mechanical and optical devices show similar heritabilities and exhibit high phenotypic and genetic correlations. Moreover, mid-infrared reflectance spectroscopy can predict MCP. The heritabilities of predicted MCP are higher than those of measured MCP, and the 2 sets of values are strongly correlated. Therefore, mid-infrared reflectance spectroscopy is a reliable and cheap method whereby MCP can be improved at the population level; this is because such spectra are already routinely acquired from the milk of cows enrolled in milk recording schemes

Volatile fingerprinting of ripened cheese for authentication and characterisation of different dairy systems

Authentication of dairy systems is of growing interest for the dairy industry and we investigated the potentiality of using volatile fingerprinting of ripened cheeses by proton transfer reaction time-of-flight mass spectrometry. A total of 1,075 individual model cheeses made from milk of individual Brown Swiss cows of 72 farms were analysed. Using a linear discriminant analysis, cows and herds were assigned to 3 or 5 dairy systems differing in management, available facilities, and diets. We obtained variable discrimination abilities (up to 77% of correct classification of cheeses and 70% of farms with cross-validation). We found m/z 61,028 (acetic acid), 109,070 (pyrazine), and m/z 137,132 (terpene) characterising model cheeses from traditional dairy systems and m/z 71,086 (3-methyl-butan-1-ol, 3-methyl-3-buten-1-ol, pentan-1-ol), m/z 101,097 (hexan-2-one, hexanal), m/z 123,117 (nonenal), m/z 129,127 (octan-1-one, octanal), and two unidentified peaks m/z 83,071 and m/z 93,090 characterising model cheeses from the modern farms. In conclusion, it seems possible to discriminate between a range of dairy systems using fast volatile fingerprinting of ripened cheeses but a proper validation of results obtained is needed.Highlights Mass spectrometry technique (PTR-ToF-MS) was able to discriminate between dairy systems. We found m/z 61,028 (acetic acid), 109,070 (pyrazine), and m/z 137,132 (terpene) characterising model cheeses from traditional dairy systems. We found m/z 71,086 (3-methyl-butan-1-ol, 3-methyl-3-buten-1-ol, pentan-1-ol), m/z 101,097 (hexan-2-one, hexanal), m/z 123,117 (nonenal), m/z 129,127 (octan-1-one, octanal), and two unidentified peaks m/z 83,071 and m/z 93,090 characterising model cheeses from the modern farms

The 9-MilCA method as a rapid, partly automated protocol for simultaneously recording milk coagulation, curd firming, syneresis, cheese yield, and curd nutrients recovery or whey loss

Abstract The aim of this study was to propose and test a new laboratory cheesemaking procedure [9-mL milk cheesemaking assessment (9-MilCA)], which records 15 traits related to milk coagulation, curd firming, syneresis, cheese yield, and curd nutrients recovery or whey loss. This procedure involves instruments found in many laboratories (i.e., heaters and lacto-dynamographs), with an easy modification of the sample rack for the insertion of 10-mL glass tubes. Four trials were carried out to test the 9-MilCA procedure. The first trial compared 8 coagulation and curd firming traits obtained using regular or modified sample racks to process milk samples from 60 cows belonging to 5 breeds and 3 farms (480 tests). The obtained patterns exhibited significant but irrelevant between-procedure differences, with better repeatability seen for 9-MilCA. The second trial tested the reproducibility and repeatability of the 7 cheesemaking traits obtained using the 9-MilCA procedure on individual samples from 60 cows tested in duplicate in 2 instruments (232 tests). The method yielded very repeatable outcomes for all 7 tested cheese yield and nutrient recovery traits (repeatability >98%), with the exception of the fresh cheese yield (84%), which was affected by the lower repeatability (67%) of the water retained in the curd. In the third trial (96 tests), we found that using centrifugation in place of curd cooking and draining (as adopted in several published studies) reduced the efficiency of whey separation, overestimated all traits, and worsened the repeatability. The fourth trial compared 9-MilCA with a more complex model cheese-manufacturing process that mimics industry practices, using 1,500-mL milk samples (72 cows, 216 tests). The average results obtained from 9-MilCA were similar to those obtained from the model cheeses, with between-method correlations ranging from 78 to 99%, except for the water retained in the curd (r=54%). Our results indicate that new 9-MilCA method is a powerful research tool that allows the rapid, inexpensive, and partly automated analysis processing 40 samples per day with 2 replicates each, using 1 lacto-dynamograph, 2 heaters, and 3 modified sample racks, and yields a complete picture of the cheesemaking process (e.g., milk gelation, curd firming, syneresis, and whey expulsion) as well as the cheese yield and the efficiency of energy or nutrients retention in the cheese or loss in the whey

genomic dna fingerprinting of indigenous chicken breeds with molecular markers designed on interspersed repeats

In Italy more than fifty different local breeds of chicken (Gallus gallus L.) are known to have been present in the past. The overall situation is now critical since most of these breeds are becoming extinct or threatened and only a few are subject of conservation plans. The use of molecular markers for the analysis of chicken populations could help in characterizing their genetic variation and preserving them from genetic erosion. valuable and irreplaceable sources of chicken germplasm from indigenous populations of the veneto region were analyzed by means of DNA fingerprinting with molecular markers designed on interspersed mini- and micros-atellite repeats. The identification of either among-breed discriminant or breed-specific markers was based on the S-SAP and M-AFLP systems derived from the AFLP technology. Genomic DNA fingerprints were generated in 84 individuals belonging to six local breeds (Ermellinata, Padovana, Pepoi, Polverara, Robusta Lionata and Robusta Maculata) and one commercial line used as reference standard. A number of variation statistics were computed to assess the genetic variability within and relatedness among breeds: the effective number of alleles per locus (ne= 1.570), total and single-breed genetic diversity (HT= 0.366 and HS= 0.209, respectively) and the fixation index (GST= 0.429). The mean genetic similarity coefficients within and between local breeds were 0.769 and 0.628, respectively. Markers useful for the genetic traceability of breeds revealed significant sequence similarities with either genic or intergenic regions of known chromosome position. Sequence tagged site primers were designed for the most discriminant markers in order to develop multiplex non-radioactive genomic PCR assays. Analysis of the population structure along with individual assignment tests successfully identified all breed clusters and subclusters. The vast majority of animals were correctly allocated to their breed of origin, demonstrating the suitability and reliability of the chosen AFLP-derived marker systems for detecting population structure and tracing individual breeds. The local breeds have been preliminarily identified according to sequence-specific SNPs and haplotypes and the polymorphism information content of genomic AFLP-derived markers is reported and critically discussed

Nitrogen excretion in dairy cow, beef and veal cattle, pig, and rabbit farms in Northern Italy

Reference values for N excretion of different livestock production systems are required for the application of the Nitrate Directive (91/676/EC). A survey aimed to estimate N excretion from on-farm measurements of feed consumption and performance of dairy cows (104 herds, 9,984 cows), growing cattle (40 farms, 40,157 young bulls), veal calves (34 farms, 49,206 calves), growing pigs (39 farms, 161,278 pigs) and rabbits (54 farms, 65,664 reproducing does) was conducted in Veneto from 2002 to 2003. N excretion was computed as the difference between N consumption and N retained in animal products. Dairy cow yielded 8,366 ± 1,646 kg/year of milk, consumed 6,600 ± 928 kg/year of DM, containing 2.45 ± 0.2 % DM of N, and excreted 116 ± 25 kg of N/year. No significant correlation was found between milk yield and N excretion, but the correlation between dietary N concentration and N excretion was significant (r=0.66). For growing cattle, the following mean values were achieved: daily gain 1.25 ± 0.19 kg/d; feed conversion ratio 6.9 ± 0.9 kg of DM/kg, rounds/year 1.66 ± 0.38. Nitrogen consumed, retained and excreted were, respectively, 68.7 ± 5.4, 11.4 ± 1.9 and 57.3 ± 4.9 kg/place/year. For veal calves, N consumed was 24.1 ± 1.9 kg/place/year, 12.1 ± 0.8 kg of which were retained in the body and 12.0 ± 1.5 kg were excreted. For heavy pig production, N consumed, per place and per year, averaged 19.0 ± 1.9 kg, N retained was 5.2 ± 0.5 kg and N excreted was 13.8 ± 0.4 kg. In the close-cycle rabbit farms, the doe and the relative growing rabbits (43 sold per year) consumed 11.2 ± 2.2 kg, retained 3.8 ± 0.7 kg and excreted 7.4 ± 1.5 kg N/doe/year. Nitrogen excretion estimated in this work can be considered as representative of some of the main animal production systems of the North-East of Italy. These values should not be considered as fixed, otherwise the implementation of the various strategies to reduce N excretion would not be possible. They should be considered as guidelines in the assistance both to public institutions and private enterprises in the evaluation of N excretion at farm level, favouring a more accurate quantification of the excretions, an increase of N retention efficiency and a better knowledge of the requirements of agricultural land. Moreover, a major extension of the agricultural land to be fertilised with manure should be promoted