Characterization of new technological and nutritional properties of milk from cows of 6 breeds reared in multi-breed herds

Improved animal production, largely as a result of genetic selection, was one of the greatest achievements of the last century. The dominant dairy cattle breed, at a global level, is the Holstein-Friesian. The breed has undergone an extreme genetic selection for several decades, towards high milk yield, and incorporated by high-nutrient and milk output systems. However, the high genetic pressure on only one trait, i.e. milk yield, resulted in unfavorable impacts on the welfare of the cows (i.e., metabolic stress, lameness, mastitis, reduced fertility and longevity). Moreover, as animals tend to adapt to the environment they are selected in, it is likely that selection for increased yield may also lead to environmental sensitivity. For instance, the negative correlation between production and fitness traits in less favorable environments is indicative of a decline in adaptability in the modern dairy cows. An increased importance exists, nowadays, for farm animal welfare that is recognized by all stakeholders in the farm animal production chain. These considerations, together with the unchanged primary goal of the dairy industry for high milk quality for the consumer’s market, has lead, in some cases, in the use of crossbreeding between Holstein-Friesian and other dairy and dual-purpose breeds. In some countries, dual-purpose breeds such as the Simmental, Montbéliarde, Normande, and specialized breeds such as the Brown Swiss and Jersey are considered the breeds of choice for crossbreeding. These breeds, including the local Italian (North-east Italy) breeds of Rendena and Alpine Grey, tend to offer superior milk quality, complemented by high beefing merits. This combination can result in increased revenue from male calves and cull cow sales. Nevertheless, comparison of milk quality of these different breeds is lacking in the literature, especially due to practical difficulties in the recording system of lots of animals, that are reared in different mixed-breed farms. To alleviate this problem, the Cowplus project has been developed at the Department of Agronomy, Food, Natural resources, Animals and Environment at University of Padova. The project permitted the sampling of 1,508 cows reared in 41 multi-breed herds, located in Trentino region in the north-eastern Italian Alps. Farms were selected from a pool of 610 herds enrolled in the Italian milk recording system. Cows were recorded for body characteristics, daily milk yield and composition, renneting aptitude, and cheese-yield. In total, 6 dairy and dual-purpose breeds were used. As part of the Cowplus project, this study aimed in: 1) the quantification and characterization of the effects of high or low herd productivity (defined according to the milk net energy yielded daily by the cows); 2) quantifying the variability of the herds within herd productivity class; 3) performing a within-herd comparison between the 3 dairy and the 3 dual-purpose breeds; 4) analyzing the effects of the days in milk (DIM) and the parity of the cows, on traditional milk quality and milk renneting aptitude (Chapter 1), cheese-making ability (Chapter 2), milk mineral elements (Chapter 3), and productivity and efficiency indicators of lactating cows (Chapter 4). More precisely, the goal of the first chapter was to test the afore mentioned effects on coagulation properties, and assess the repeatability and reproducibility of traditional milk coagulation properties (MCP) and curd-firming over time (CFt) modeled and derived traits. Milk samples were collected from all the 1,508 cows and analyzed in duplicates (3,016 tests) using two lactodynamographs (Formagraph, FOSS) to obtain 240 curd-firmness (CF) measurements in 60 min (one every 15 sec) for each duplicate. Results showed that the effect of herd-date on the traditional and modeled MCP was modest while individual animal variance showed the highest incidence. The repeatability of MCP was high (> 80%) for all traits excluding those depending on the last part of the lactodynamographic curve (57 to 71%). The reproducibility, taking also into account the effect of instrument, was equal or slightly lower than repeatability. Milk samples collected in farms characterized by high level of productivity exhibited delayed coagulation but greater potential curd firmness compared to milk samples collected from low productivity herds. Large differences in all MCP traits were observed among breeds, both between specialized and dual-purpose breeds, and within the two groups, even after adjusting for milk quality and yield. Milk samples from Jersey cows, both for milk quality and MCP, and also from Rendena cows (but only for coagulation time) were superior respect to milk from Holstein-Friesian cows, while intermediate results were found for the other breeds of Alpine origin. The second chapter aimed at evaluating the same effects on 508 model cheeses derived from 508 cows of 6 different breeds. For each cow 6 milk composition traits, 4 recovery traits (REC) of milk nutrients (fat, protein, solids and energy) in the curd, and 3 actual % cheese yield traits (%CY), expressing the fresh cheese, cheese solids and cheese water as percentages of the processed milk were analyzed (these traits were obtained during the experimental cheese-making process). In addition, 2 theoretical %CYs (fresh cheese and cheese solids) were calculated from the milk composition, and 2 overall cheese-making efficiencies (fresh cheese and cheese solids) were calculated as the % ratio between actual and theoretical %CYs. Daily milk yield (dMY) was also measured and estimates were made of 3 actual daily cheese yield production traits (dCY) per cow (fresh cheese, cheese solids and water retained in the cheese). Results showed that cows reared in high productivity herds yielded more milk with greater nutrient contents and more cheese per day, and had greater theoretical %CY, although to a lesser extent, actual %CY. However, they did not differ from low productivity herds in terms of REC traits (except solids), while they had a lower solid cheese-making efficiency. Individual herds within productivity classes were an intermediate source of total variation with respect to REC traits (11.3% to 17.1%), and to actual and theoretical %CY and estimates of efficiency (10.0% to 17.2%), and a major source for milk yield and dCY traits (43.1% to 46.3%). Breed within herd greatly affected all traits. Compared with the dual-purpose breeds, the 3 specialized dairy breeds (Holstein, Brown Swiss and Jersey) had, on average, a similar dMY, better milk composition, greater actual and theoretical %CY, similar fat and protein REC, and slightly lower cheese-making efficiency. Of the specialized dairy cow breeds, Holsteins produced more milk, but Brown Swiss cows produced milk with a greater nutrient content, greater nutrient REC, higher actual and theoretical %CY and a higher cheese-making efficiency, so the two large breeds had the same dCY. Small Jersey cows produced much less milk, with much more fat and protein and greater REC traits than the two large-framed breeds resulting in greater actual and theoretical %CY but similar efficiencies. Although the Jersey breed had lower dMY and dCY, the difference was much smaller for the latter. The differences among Simmental and the local Rendena and Alpine Grey were not very large. Compared with medium-framed cows of the local breeds, Simmentals had greater dMY, tended to have better milk composition, REC and %CY traits (but similar efficiencies), and also had much greater dCY. Among the local breeds, the higher dMY of Rendena was offset by the greater nutrient content of milk from the Alpine Greys, so their dCY was similar. The objective of the third chapter was to test the same previous effects on 240 milk samples from 240 cows of 6 different breeds. Fifteen minerals were determined by Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES). Results revealed that the effect of herd-date was large especially on environmental minerals (from 47 to 91% of the total variance), while it ranged from 11% to 61% considering both macro- and micro-minerals. Milk samples collected in farms characterized by high level of productivity exhibited richer mineral profile compared to milk samples collected from low productivity herds. Parity influenced exclusively macro-minerals, with the exception of Ca and S, while DIM influenced almost all minerals, with few exception related to the environmental elements. Large differences were observed among breeds, both between specialized and dual-purpose breeds, even after adjusting for milk quality and yield. Milk samples from Jersey and Brown Swiss cows were superior respect to milk from Holstein-Friesian cows, both for milk quality and mineral profile, while intermediate results were found for the other breeds of Alpine origin. Moreover, the variance of individual animals was much greater than variance of individual herds within herd productivity class. The fourth chapter focused on the concepts of production, productivity and efficiency. As breed of cows and herd characteristics are the most important factors affecting milk productivity and efficiency, the aim of this chapter was to obtain independent evaluation of these factors on the data (body size and production) and milk characteristics from the 41 multi-breed herds on all 1,508 lactating cows from the 6 breeds. Nine productivity indicators and two simplified indicators of cow efficiency for cheese production, one energetic and one economic, were calculated. Results showed that breed within herd greatly affected all traits. On average the 3 dairy breeds were not much different from the 3 dual-purpose breeds, but large differences characterized both groups of cows. Jersey cows were the less productive, but, after correcting for herds effect and scaling for body size, they showed the highest efficiency among the dairy breeds. Holstein was the most productive dairy breed, but Brown Swiss cows had better milk quality and more efficient cheese-making aptitude and thus produced more cheese per day than Holsteins. Dual-purpose breeds were less variable than dairy ones, with Simmental with larger body size and production, but not productivity and efficiency respect to local Rendena and Alpine Grey breeds. If on one hand within herd comparison and correctly scaling of production traits reduced strongly herd differences in productivity, on the other hand they did not reduce very much the differences in terms of milk composition, technological properties and efficiency of cheese-making (recovery of milk nutrients in cheese), so that the differences among breeds remained strong and their importance on the overall efficiency evaluation of the breeds increased

Detailed macro- and micromineral profile of milk: Effects of herd productivity, parity, and stage of lactation of cows of 6 dairy and dual-purpose breeds

The aim of this study was to quantify the major sources of variation in the levels of 15 minerals in individual milk samples collected from cows raised in multibreed dairy herds. The herds (n = 27) were classified into 2 categories, according to milk productivity. Milk productivity was based on the net energy of lactating cows' average daily milk yield. Milk samples were collected from 240 cows of 6 different breeds: 3 specialized dairy (Holstein-Friesian, Brown Swiss, and Jersey) and 3 dual-purpose (Simmental, Rendena, and Alpine Grey). The samples were analyzed for macro-elements (Na, Mg, P, S, K, and Ca), essential micro-elements (Mn, Fe, Cu, Zn, and Se), and environmental micro-elements (B, Si, Sr, and Sn), using inductively coupled plasma-optical emission spectrometry. Data were analyzed using a linear mixed model that included fixed effects of days in milk (DIM), parity, breed, and herd productivity, and a random effect of herd-date within productivity level. Results showed that the effect of herd-date varied across minerals. It was especially large for environmental minerals (ranging from 47 to 91% of total variance) and ranged from 11 to 61% for macrominerals and essential microminerals. Milk samples collected from farms with a high level of herd productivity had a richer mineral profile than samples from low-productivity herds. Parity only influenced macrominerals, with the exception of S and Ca, while DIM influenced almost all minerals, with a few exceptions among the environmental elements. Differences in mineral profile were small between specialized and dual-purpose breeds, but they were large within the group of the specialized cows. These breed differences were reduced after adjusting for milk quality and yield, particularly in the case of milk Mg, S, Ca, Mn, and Zn levels. Milk samples from the Jersey and Brown Swiss cows had higher mineral levels (Sn excluded) than milk from the Holstein-Friesian cows; the other breeds of Alpine origin produced milk of intermediate quality. Our findings suggest that breed has a stronger effect on macrominerals and some of the essential microminerals than herd productivity, parity, and DIM. The modification of the mineral profile in milk seems possible for many minerals, but it likely depends on genetics (e.g., breed, selection) and on environmental and management factors in variable proportions according to the mineral considered

Breed of cow and herd productivity affect milk nutrient recovery in curd, and cheese yield, efficiency and daily production.

Little is known about cheese-making efficiency at the individual cow level, so our objective was to study the effects of herd productivity, individual herd within productivity class and breed of cow within herd by producing, then analyzing, 508 model cheeses from the milk of 508 cows of six different breeds reared in 41 multi-breed herds classified into two productivity classes (high v. low). For each cow we obtained six milk composition traits; four milk nutrient (fat, protein, solids and energy) recovery traits (REC) in curd; three actual % cheese yield traits (%CY); two theoretical %CYs (fresh cheese and cheese solids) calculated from milk composition; two overall cheese-making efficiencies (% ratio of actual to theoretical %CYs); daily milk yield (dMY); and three actual daily cheese yield traits (dCY). The aforementioned phenotypes were analyzed using a mixed model which included the fixed effects of herd productivity, parity, days in milk (DIM) and breed; the random effects were the water bath, vat, herd and residual. Cows reared in high-productivity herds yielded more milk with higher nutrient contents and more cheese per day, had greater theoretical %CY, and lower cheese-making efficiency than low-productivity herds, but there were no differences between them in terms of REC traits. Individual herd within productivity class was an intermediate source of total variation in REC, %CY and efficiency traits (10.0% to 17.2%), and a major source of variation in milk yield and dCY traits (43.1% to 46.3%). Parity of cows was an important source of variation for productivity traits, whereas DIM affected almost all traits. Breed within herd greatly affected all traits. Holsteins produced more milk, but Brown Swiss cows produced milk with higher actual and theoretical %CYs and cheese-making efficiency, so that the two large-framed breeds had the same dCY. Compared with the two large-framed breeds, the small Jersey cows produced much less milk, but with greater actual and theoretical %CYs, similar efficiencies and a slightly lower dCY. Compared with the average of the specialized dairy breeds, the three dual-purpose breeds (Simmental and the local Rendena and Alpine Grey) had, on average, similar dMY, lower actual and theoretical %CY, similar fat and protein REC, and slightly greater cheese-making efficiency

Milk yield, quality, and coagulation properties of 6 breeds of goats: Environmental and individual variability.

ABSTRACT Goat milk and cheese production is continuously increasing and milk composition and coagulation properties (MCP) are useful tools to predict cheesemaking aptitude. The present study was planned to investigate the extension of lactodynamographic analysis up to 60 min in goat milk, to measure the farm and individual factors, and to investigate differences among 6 goat breeds. Daily milk yield (dMY) was recorded and milk samples collected from 1,272 goats reared in 35 farms. Goats were of 6 different breeds: Saanen and Camosciata delle Alpi for the Alpine type, and Murciano-Granadina, Maltese, Sarda, and Sarda Primitiva for the Mediterranean type. Milk composition (fat, protein, lactose, pH; somatic cell score; logarithmic bacterial count) and MCP [rennet coagulation time (RCT, min), curd-firming time (k20, min), curd firmness at 30, 45, and 60 min after rennet addition (a30, a45, and a60, mm)] were recorded, and daily fat and protein yield (dFPY g/d) was calculated as the sum of fat and protein concentration multiplied by the dMY. Data were analyzed using different statistical models to measure the effects of farm, parity, stage of lactation and breed; lastly, the direct and the indirect effect of breed were quantified by comparing the variance of breed from models with or without the inclusion of linear regression of fat, protein, lactose, pH, bacterial, somatic cell counts, and dMY. Orthogonal contrasts were performed to compare least squares means. Almost all traits exhibited high variability, with coefficients of variation between 32 (for RCT) and 63% (for a30). The proportion of variance regarding dMY, dFPY, and milk composition due to the farm was moderate, whereas for MCP it was low, except for a60, at 69%. Parity affected both yield and quality traits of milk, with least squares means of dMY and dFPY showing an increase and RCT and curd firmness traits a decrease from the first to the last parity class. All milk quality traits, excluding fat, were affected by the stage of lactation; RCT and k20 decreased rapidly and a30 was higher from the first to the last part of lactation. Alpine breeds showed the highest dMY and dFPY but Mediterranean the best percentage of protein, fat, and lactose and a shorter k20 and a greater a30. Among the Mediterranean goats, Murciano-Granadina goats had the highest milk yield, fat, and protein contents, whereas Maltese, Sarda, and Sarda Primitiva were characterized by much more favorable technological properties in terms of k20, a30, and a45. In conclusion, as both the farm and individual factors highly influenced milk composition and MCP traits, improvements of these traits should be based both on modifying management and individual goat factors. As expected, several differences were attributable to the breed effect, with the best milk production for the Alpines and milk quality and coagulation for the Mediterranean goats

Effect of composition on coagulation, curd firming, and syneresis of goat milk.

The present study investigated the effect of different levels of fat, protein, and casein on (1) traditional milk coagulation properties, and (2) curd firming over time parameters of 1,272 goat milk samples. Relationships between fat, protein, and casein and some indicators of udder health status (lactose, pH, somatic cells, bacterial count, and NaCl) were also investigated. Traditional milk coagulation properties and modeled curd-firming parameters were analyzed using a mixed model that considered the effect of days in milk, parity, farm, breed, the pendulum of the instrument, and different levels of fat, protein, and casein. Fat, protein, and casein were also tested with the same model but one at a time. Information provided by this model demonstrated the effect of one component alone, without contemporarily considering that of the others. The results allowed us to clarify the effect of the major milk nutrients on coagulation, curd firming, and syneresis ability of goat milk. In particular, milk rich in fat was associated with better coagulation properties, whereas milk rich in protein was associated with delayed coagulation. The high correlation of fat with protein and casein contents suggests that the effect of fat on the cheese-making process is also attributable to the effects of protein and casein. When only protein or only casein was included in the statistical model, the pattern of coagulation, curd firming, and syneresis was almost indistinguishable. The contemporary inclusion of protein and casein in the statistical model did not generate computing problems and allowed us to better characterize the role of protein and casein. Consequently, given their strong association, we also tested the effect of casein-to-protein ratio (i.e., casein number). Higher values of casein number led to a general improvement in the coagulation ability of milk, suggesting that casein-to-protein ratio, not just protein or casein, should be considered when milk is destined for cheese making. These results are especially useful for dairy farmers who want to increase their profits by improving the technological quality of the milk produced

Cheesemaking in highland pastures: Milk technological properties, cream, cheese and ricotta yields, milk nutrients recovery, and products composition

Summer transhumance of dairy cows to high Alpine pastures is still practiced in many mountainous areas. It is important for many permanent dairy farms because the use of highland pastures increases milk production and high-priced typical local dairy products often boost farm income. As traditional cheese- and ricotta-making procedures in Alpine pastures are central to this dairy system, the objective of this study was to characterize the quality and efficiency of products and their relationships with the quality and availability of grass during the grazing season. The milk from 148 cows from 12 permanent farms reared on a temporary farm located in Alpine pastures was processed every 2 wk during the summer (7 cheesemakings from late June to early September). During each processing, 11 dairy products (4 types of milk, 2 by-products, 3 fresh products, and 2 ripened cheeses) were sampled and analyzed. In addition, 8 samples of fresh forage from the pasture used by the cows were collected and analyzed. At the beginning of the pasture season the cows were at 233 \ub1 90 d in milk, 2.4 \ub1 1.7 parities, and produced 23.6 \ub1 5.7 kg/d of milk. The milk yield decreased with the move from permanent to temporary farms and during the entire summer transhumance, but partly recovered after the cows returned to the permanent farms. Similar trends were observed for the daily yields of fat, protein, casein, lactose, and energy, as we found no large variations in the quality of the milk, with the exception of the first period of Alpine pasture. The somatic cell counts of milk increased during transhumance, but this resulted from a concentration of cells in a lower quantity of milk rather than an increase in the total number of cells ejected daily from the udder. We noted a quadratic trend in availability of forage (fresh and dry matter weight per hectare), with a maximum in late July. The quality of forage also varied during the summer with a worsening of chemical composition. The evening milk (before and after natural creaming), the whole morning milk, and the mixed vat milk had different chemical compositions, traditional coagulation properties, and curd-firming modeling parameters. These variations over the pasture season were similar to the residual variations with respect to chemical composition, and much lower with respect to coagulation and curd-firming traits. Much larger variations were noted in cream, cheese, and ricotta yields, as well as in nutrient recoveries in curd during the pasture season. The protein content of forage was correlated with some of the coagulation and curd-firming traits, the ether extract of forage was positively correlated with milk fat content and cheese yields, and fiber fractions of forage were unfavorably correlated with some of the chemical and technological traits. Traditional cheese- and ricotta-making procedures showed average cream, cheese, and ricotta yields of 6.3, 14.2, and 4.9%, respectively, and an overall recovery of almost 100% of milk fat, 88% of milk protein, and 60% of total milk solids

Prediction accuracies of cheese-making traits using Fourier-transform infrared spectra in goat milk

The objectives of this study were to explore the use of Fourier-transform infrared (FITR) spectroscopy on 458 goat milk samples for predicting cheese-making traits, and to test the effect of the farm variability on their prediction accuracy. Calibration equations were developed using a Bayesian approach with three different scenarios: i) a random cross-validation (CV) [80% calibration (CAL); 20% validation (VAL) set], ii) a stratified CV [(SCV), 13 farms used as CAL, and the remaining one as VAL set], and iii) a SCV where 20% of the goats randomly selected from the VAL farm were included in the CAL set (SCV80). The best prediction performance was obtained for cheese yield solids, justifying for its practical application at population level. Overall results were similar to or outperformed those reported for bovine milk. Our results suggest considering specific procedures for calibration development to propose reliable tools applicable along the dairy goat chain

Effects of indirect indicators of udder health on nutrient recovery and cheese yield traits in goat milk

In dairy goats, very little is known about the effect of the 2 most important indirect indicators of udder health [somatic cell count (SCC) and total bacterial count (TBC)] on milk composition and cheese yield, and no information is available regarding the effects of lactose levels, pH, and NaCl content on the recovery of nutrients in the curd, cheese yield traits, and daily cheese yields. Because large differences exist among dairy species, conclusions from the most studied species (i.e., bovine) cannot be drawn for all types of dairy-producing animals. The aims of this study were to quantify, using milk samples from 560 dairy goats, the contemporary effects of a pool of udder health indirect indicators (lactose level, pH, SCC, TBC, and NaCl content) on the recovery of nutrients in the curd (%REC), cheese yield (%CY), and daily cheese yields (dCY). Cheese-making traits were analyzed using a mixed model, with parity, days in milk (DIM), lactose level, pH, SCC, TBC, and NaCl content as fixed effects, and farm, breed, glass tube, and animal as random effects. Results indicated that high levels of milk lactose were associated with reduced total solids recovery in the curd and lower cheese yields, because of the lower milk fat and protein contents in samples rich in lactose. Higher pH correlated with higher recovery of nutrients in the curd and higher cheese yield traits. These results may be explained by the positive correlation between pH and milk fat, protein, and casein in goat milk. High SCC were associated with higher recovery of solids and energy in the curd but lower recovery of protein. The higher cheese yield obtained from milk with high SCC was due to both increased recovery of lactose in the curd and water retention. Bacterial count proved to be the least important factor affecting cheese-making traits, but it decreased daily cheese yields, suggesting that, even if below the legal limits, TBC should be considered in order to monitor flock management and avoid economic losses. The effect of NaCl content on milk composition was linked with lower recovery of all nutrients in the curd during cheese-making. In addition, high milk NaCl content led to reductions in fresh cheese yield and cheese solids. The indirect indicators of the present study significantly affected the cheese-making process. Such information should be considered, to adjust the milk-to-cheese economic value and the milk payment system