Ria-3-2011(solo-en-ingles)_maquetación 1.qxd

RIA / Vol. 37 / N.À 2 Study and evolution of the qualityof raw milk from dairy farms in thenorthwest of the province of Santa Feand south of the province of Santiagodel Estero, Argentina (1993 – 2009) REVELLI, G.R.1; SBODIO, O.A.2; TERCERO, E.J.2 A total of 10,704 raw milk samples from a bulk tank were collected on 55 dairy farms associated to the Coo- perativa Tambera y Agropecuaria Nueva Alpina Ltda. between 1993 and 2009. Physicochemical, microbiologicaland sanitary parameters were analyzed within the framework of the Comprehensive Milk Quality ImprovementProgram to determine the mean values that characterize the zone. The following values were found: Acidity:16.30 ± 0.96 °D, pH: 6.68 ± 0.04, Fat: 3.48 ± 0.24%, True Protein: 3.11 ± 0.12%, Lactose: 4.74 ± 0.16%, Ash:0.70 ± 0.09%, Total Solids: 12.18 ± 0.42%, Freezing Point: -0.530 ± 0.02 °C, Total Bacterial Count: 9.6 x 104± 2.2 x 105 CFU/ml, Somatic Cell Count: 407,000 ± 230,000 cells/ml and Antibiotic Residues: 99.64% Negative.
The most significant correlations were: Fat vs Total Solids (r = 0.784; P < 0.001) and True Protein vs TotalSolids (r = 0.557; P < 0.001). The compositional quality of raw milk from dairy farms in the northwest of SantaFe and south of Santiago del Estero were studied over a period of 17 years and showed a significant improve-ment, particularly regarding the indicators that infer a high industrial value. Optimization of the producers' ma-nagement capacity and the operational quality of dairy farmers contributed to achieve these results.
Keywords: lactology, zonal characterization, comprehensive training.
of hormonal changes, proliferate and develop during gesta-tion and achieve full synthetic activity almost at the time of Milk is the secretion of the mammary glands that is pro- giving birth (Homan and Wattiaux, 1996).
duced to feed the offspring of female mammals. Milk hasnumerous constituents in different states of dispersion Milk composition determines its nutritional quality and wherefore understanding its properties and the many chan- value as raw material for food preparation; many of its pro- ges that occur in milk requires knowing all its elements and perties differ depending on the breed, individual, number of their interaction. births, lactation stage, feed and number of milkings, amongothers (Veisseyre, 1980). This unique product secreted by the mammary glands under a complex hormonal control includes over 100,000 Milk quality is important not only from the viewpoint of pu- different molecular species and is synthesized in secretory blic health but also from that of the industry. Milk quality de- cells of the mammary secretory epithelium which, as a result pends on its general composition, mineral content, aroma, 1 Laboratorio Integral de Servicios Analíticos (L.I.S.A.), Cooperativa Tambera y Agropecuaria Nueva Alpina Ltda., S2340ALB Ceres,Santa Fe, Argentina. E-mail: [email protected] Instituto de Tecnología de Alimentos (I.T.A.), Facultad de Ingeniería Química, Universidad Nacional del Litoral, Casilla de Correo 266,Santa Fe, Argentina.
Received August 12th 2010 // Accepted April 11th 2011 // Published online June 08th 2011
Study and evolution of the quality of raw milk from dairy farms in the northwest of the province of Santa Fe and south. August 2011, Argentina presence of contaminants, properties, etc., and obviously systematic use of a comprehensive milk quality improve- involves all the sectors that participate in primary production, ment program including the different production-related va- conservation, transport, storage and transformation (Sbodio riables and its evolution have been performed. et al., 1988). Healthy, genetically fit animals, adequate fee-ding and management, good hygiene practices, control of The objective of this study was to characterize the physi- mastitis and other pathologies are indispensable to guaran- cochemical, microbiological and sanitary composition of raw tee safe, whole and healthy products for consumers (La- milk and observe its evolution over the period 1993 - 2009.
grange, 1979; Marth, 1981). GENERAL PRODUCTION CONDITIONS
In Argentina, the quality of milk has been characterized in numerous studies, particularly those that surveyed the Cen-tral Dairy Basin and most of them report the negative inci- The study included 55 dairy farms that are members of dence of conditioning factors such as microbiological the "Cooperativa Tambera y Agropecuaria Nueva Alpina contamination, mastitis, heat stress, feed, quality of drinking Ltda." Which are geographically located within a 25-Km ra- water for the animals, etc., on milk production, composition dius of the town of Colonia Alpina (30° 4' S – 62° 6' W – 95 and properties that cause significant losses in processing, m.a.s.l.), District of Rivadavia in the Province of Santiago yield and quality of the end product (Weidmann et al., 1980; del Estero, Argentina.
Sbodio et al., 1981, 1985, 1988, 1989, 1992, 1994, 1996,1997, 1999b, 2007; Tessi, 1981; Simoneta, 1987; Garat et Climate and Soils
al., 1989; Calvinho et al., 1991; Totoni, 1994; Minetti et al.,1995; Izak et al., 1998; Reinheimer, 1998; Páez et al., 2001; The area has a warm climate with short, cool winters and Revelli and Rodríguez, 2001; Tavern et al., 2001a,b,c,d,e; very warm, rigorous summers.
Revelli et al., 2002, 2004a,c,d, 2005, 2007; Valtorta et al., Mean annual temperature is 19.0ºC (N-S variation = 2002; Zannier et al., 2002; Gallardo, 2003).
1.5ºC) and mean annual rainfall is 1,025 mm (W-E variation Programs that require physicochemical, microbiological = 75 mm). The winters are dry and approximately 70% of and sanitary testing and enable the implementation of pay- the rainfall occurs in the summer and fall seasons. Predo- ment for quality systems are currently in place (FIL-IDF, minant winds are from the North and South.
1985; Sargeant et al., 1998; Revelli, 2000; Center for Food Absolute maximum temperatures registered in the sum- Safety & Applied Nutrition, 2002), and are extremely impor- mer are close to 39 - 40ºC and are an important cause of tant as they define the price paid to the farmers. environmental stress for the normal development of lives- Payment systems implemented by most milk receiving tock farming activities such as milk production (Valtorta et companies include variables such as: volume produced, al., 2002). Absolute minimum winter temperatures are bet- temperature, acidity, milk fat, raw protein, total solids, non- ween -4 and -5ºC.
fatty solids, cryoscopic drop, total bacterial count, somatic The climate in the region is "anomalous". Around the cell count, antibiotics, brucellosis, tuberculosis and, more re- world, regions near Latitude 30º have higher temperatures cently, chlorinated and phosphorous pesticides. These indi- in summer and lower in winter than what they should have cators are used to determine payment of premiums and/or at this latitude. In this area of Argentina, summers are war- apply penalties, as applicable, and the end price for raw ma- mer that in regions 100 Km further north, and winters are terial paid to the farmers. In the specific case of SanCor Co- colder than in regions 100 Km further south (Barrucand and operativas Unidas Ltda., the company pays a 4% premium Rusticucci, 2001).
for a category known as "Leche Plus" (Premium Milk) formilk that meets the quality parameters and provided the far- With a surface area of approximately 30,000 ha, these mers apply a comprehensive system of Good Agricultural plains have a partially acid typical Argiudol soil with silt loam texture containing sufficient or moderately sufficient organicmatter. The soil has moderately good drainage and very low Sbodio et al. (1996) analyzed the composition, hygiene sand content. The water table is usually at a depth of 10 m.
and sanitary parameters of the milk produced in the area in- Development of argillic horizons causes moderate restric- cluded in this study and determined that the quality was ac- tions. These soils are dominant only in areas with better drai- ceptable but could potentially be limited by deficiencies in nage but, in general, form Aquic Argiudoll and typical nutritional requirements and inadequate management prac- Argialbol complexes. In the gullies, predominant soils have tices. The same authors evaluated the proteolytic activity of poor drainage and are sodic or saline-sodic of the typical Na- native and non-native enzymes in milk intended for the che- tracualf type with silt loam texture, slightly acid and poor in ese industry and noted that an acceptable hygiene and sa- organic matter. To the west of Colonia Alpina there are typical nitary quality resulted in moderate proteolytic activity Haplustol and Natracualf soils with silt loam texture, good to whereas low hygiene and sanitary quality increased hydroly- moderately good organic matter content and slight to mode- tic activity sufficiently to modify the physicochemical charac- rate acidity (Hein and Panigatti, 1986; Giorgi et al., 2008).
teristics of αs1, αs2 and β caseins which alter coagulationfitness and cause undesirable odors and flavors (Sbodio et Predominant activity is intensive cattle farming (dairy and al., 1999a). However, no studies that report the results of a fattening on alfalfa-based pastures), agriculture in areas with REVELLI, G.R.1; SBODIO, O.A.2; TERCERO, E.J.2 RIA / Vol. 37 / N.À 2 high and medium productive capacity, and stocking opera- The diet of milking cows is adjusted according the requi- tions in areas with low quality soils (Melo, 2005). Main agri- rements of their lactation stage and other factors such as cultural crops are alfalfa, maize, soy and wheat although pregnancy and body condition. Animals with similar requi- there are local differences and sorghum, sunflower, oats and rements are grouped together. Normally the leading lot foxtail millet are also grown in some areas.
(Herd No. 1) includes non-gravid cows at 120 days lactationwith a body condition score of 2 – 2.5. The diet of these Recent studies in the area performed by Revelli et al. cows is adequate to reach a good lactation peak and the (2010) determined that in recent years the pH of the soil ten- energy level of the diet is determined by the expected pro- ded to become more acid therefore there was a need to apply reduced tilling systems, promote the development oforganic matter and adopt crop rotation patterns to ensure The diet for dry cows has a good anionic-cationic balance the sustainability of the soil in the region.
to prevent metabolic disorders such as hypocalcaemia andoptimize production and reproductive yield in the next lac- Breeds and Genetic Improvement
tation (Maiztegui, 2009). At least 40 days before calving,cows are fed a diet that meets their needs and which usually The predominant breed is Holstein. Since 2000 to date, includes foxtail millet rolls, corn silage, alfalfa rolls and the "Cooperativa Tambera y Agropecuaria Nueva Alpina grains as well as anionic salts, if necessary.
Ltda." promotes the Dairy Cattle Genetic Improvement Pro-gram developed by Genética e Inseminación Artificial Alpina In all cases, mineral and vitamin supplements are added (GENIAL®) based on selection of animals according to an to cover the requirements of the diet fed to the animals. economic index known as Dairy Economic Genetic MeritIndex (Mérito Genético Económico Lechero) (MEGEL®).
To improve the profitability of dairy farms, animals that In the region where the study was conducted aquifers are make better use of forage resources and are more efficient highly mineralized and greatly exceed recommended values in converting feed (expressed in tons of DM consumed) into for cattle consumption (Revelli et al., 2002). Salinity levels net income (expressed in $) are brought on the farms to mi- increase with depth and the presence of toxic elements such nimize production costs and therefore gain higher profits.
as arsenic are conditioning factors for underground water The best cows are graded, crossed with the best bulls and use. The same authors also studied the performance of low the young bulls that are born are used to inseminate the production grazing cows (<25 l/cow/day) exposed to diffe- cows on the dairy farms thus providing continuity to the ani- rent levels of salinity in drinking water and found no signifi- mal genetic improvement cycle (Gagliardi and López-Villa- cant differences in production levels although milk fat lobos, 2006).
content was 8.5% higher in milk produced by cows thatdrank high-salinity water. As a result, total solids were signi- The system also requires selection and assisted inclusion ficantly higher (2.6%) (Revelli et al., 2005).
on the dairy farms of animals that carry allele *0902 of theBoLA-DRB3.2 gene that provides genetic resistance to en- However, a recent experiment with high production cows zootic bovine leukosis (GENIAL BVL-R semen) with the pur- ( 32 l/cow/day) showed no significant difference in produc- pose of controlling and eventually eradicating the disease tion and milk composition which could be attributed to the (Esteban et al., 2009).
buffer effect of the rumen (Valtorta et al., 2008).
Feeding of the Dairy Herds
Feeding of the animals is based on direct grazing of alfalfa In the period 1999-2002 Uberti and Revelli (2002) repor- and continuous supplementation (70/30 grass/concentrate ted a low prevalence of bovine brucellosis. Currently, in summer months and 50/50 in winter). 94.12% of the dairy farms evaluated are officially certifiedas free of the disease, 88.24% are free of bovine tuberculo- Given the edaphoclimatic conditions of the area, dairy sis and the remaining 11.76% apply a stringent control and herds are mainly fed alfalfa and maize. Alfalfa is well adap- ted to the region and yields over 9 tn DM/Ha/year in fieldconditions. The crop is seeded alone as the survival of other The results for enzootic bovine leukosis were not so pro- crops sown in consociation is low and mainly 8 and 9 growth mising and the reported prevalence was 30.51%. 97.44% of groups are used. Maize is fundamental for grain and silage the animals on the dairy farms included in the study were production and is included to balance the diet of dairy cows seropositive (values were between 4.17 and 73.58%) (Re- and support the stocking rate. Yield in the area is 8 – 10 tn velli et al., 2004b).
Milk Quality Management Program
The nutritional program also includes winter greenfeeds (oats and wheat) and summer greenfeeds such as forage In response to the previously described situation in the sorghum and other crops including foxtail millet and grain area, farmers decided to test and learn about their raw ma- terial in order to use the information as a corrective tool and Study and evolution of the quality of raw milk from dairy farms in the northwest of the province of Santa Fe and south. August 2011, Argentina justify an adequate return from the industry. For this pur- Snap™ Beta Lactam Test Kit – IDEXX Laboratories, Inc., pose, they formed a cooperative: "Cooperativa Tambera y Snap™ Tetracycline Test Kit – IDEXX Laboratories, Inc. and Agropecuaria Nueva Alpina Ltda." and developed their own CMT Copan Milk Test – Copan Diagnostics Inc.
quality management system, the Comprehensive Milk Qua-lity Improvement Program. In 1993 they opened a laboratory The statistical analysis of the data was performed using ("Laboratorio Integral de Servicios Analíticos" -L.I.S.A.-) and the following modules of the STATISTICA 8.0 (2008) soft- a signed a historical agreement with the "Instituto de Tec- ware: Basic Statistics and Tables (Descriptive Statistics – nología de Alimentos" (I.T.A.) of the School of Chemical En- Matrix Correlation), Nonparametric Statistics and Distribu- gineering of the National University of Littoral. This tion Fitting (Inferential Statistics – Hypothesis Test) (Snede- development included the design of civil works, selection of cor and Cochran, 1977).
reference analytical methods, equipment and training of SURVEY OF THE INITIAL SITUATION, YEAR 1993
human resources. The study began in 1993 with a survey of the initial situa- The system applies a preventive program that includes tion on 16 representative dairy farms that were members of diagnosis and traceability based on concepts that respond to the "Cooperativa Tambera y Agropecuaria Nueva Alpina the culture and productive structures of the region and an in- Ltda.". A total of 143 samples from a bulk tank were collec- genious communication method of "alarms" allowing prompt ted. These farms had low production, uncertainty about the implementation of corrective actions, particularly in regard to raw material they produced, high prevalence of mastitis, no microbiological contamination and mastitis. Operational con- adequate hygiene or feeding routines and no quality controls trols include: work routines, milking equipment, coolers, ef- for their inputs. Most farms had precarious infrastructure.
fectiveness of clinical and drying treatments and quality of Important to note is that the members had a firm decision to inputs used on the farm (sanitation products, teat dip, feed, improve in all areas. To this end, technical advice recom- etc.). Additionally, visits and meetings are organized with the mended that the physicochemical, hygiene and health com- participation of technicians and agricultural and dairy farmers position of the milk be determined first and then the general to create an environment that fosters comprehensive training production conditions. Tests were performed at the Central of all players involved in production (Revelli, 2000).
Laboratory of the Food Technology Institute (I.T.A.) of theSchool of Chemical Engineering of the National University SAMPLING DESIGN AND ANALYTICAL METHODO-
of Littoral. Results for the indicators that were tested showed that the quality of the milk produced in the area was regular In the period 1993 – 2009, specially trained staff of the to low, particularly since average acidity (18.33 ºD), total L.I.S.A. laboratory collected raw milk samples (n = 10,704) bacteria count (3.2 x 105 CFU/ml) and somatic cell count from a bulk tank every 15 days as required by the Compre- (687,000 SC/ml) were high indicating contamination and hensive Milk Quality Improvement Program to characterize mastitis. Additionally, mean concentrations of milk fat each farm included in the study (Revelli, 2000). Samples (3.27%), true protein (2.86%), lactose (4.59%) and total so- were collected in sterile, 120 ml screw cap plastic containers lids (11.52%) were very low indicating important nutritional and the same criteria applied by the receiving company (SanCor Cooperativas Unidas Ltda.) to evaluate the quality Milk obtained from cows with good nutritional condition and pay the farmers (a representative volume of the total and management in the Central Milk Basin of Argentina, ad- quantity of milk in the tank taken when the milk is collected) jacent to the tested area and used as a reference, showed was used. Samples were sent chilled at 7ºC to the labora- to have a better composition (Weidmann et al., 1980; Sbodio tory with no addition of preservatives and analyzed within et al., 1985, 1988; Garat et al., 1989), with high content of 24 hours of collection.
milk fat and true proteins. The following methodologies were used to evaluate the se- EVOLUTION OF THE DAIRY FARMS AND SAMPLES
lected indicators: Acidity (ºD): IRAM Standard 14005: 1976, pH (pH): Potentiometry - Horiba Cardy Twin B-113 (Kyoto,Japan), Milk fat (%MF): Nephelometry – Butilac S-190 (SIEM The total number of dairy farms and samples tested du- S.R.L. Córdoba, Argentina) calibrated vs Rose Göttlieb, True ring the period of the study is shown in Figure 1.
Protein (%TP) [TP = (TN – NPN) x 6.38]: FIL-IDF Standard20B: 1993 – Kjeldahl Foss Tecator (Höganäs, Sweden), Lac- In the last 17 years of the study the number of dairy farms tose (%LACTOSE) and Total Solids (%TS): AOAC Standard decreased significantly and, therefore, of samples collected.
Method – Infrared Absorption Spectroscopy, Ashes The Comprehensive Milk Quality Improvement Program mo- (%ASHES): AOAC Standard 16035: 1975, Cryoscopic Des- nitored the highest number of dairy farms in 1995 (45 cent (°C): FIL-IDF Standard 108B: 1991 – Funke Gerber farms). This number remained stable until 2002 but then CryoStar Economy II GmbH (Munchen, Germany), Total dropped sharply as of 2003 so that at the end of the study Bacteria Count (TBC): FIL-IDF Standard 100B: 1991, Soma- (in 2009) only 17 dairy farms were included in the system.
tic Cell Count (SCC): FIL-IDF Standard 148A: 1995 and In- Most of the establishments that did not continue with the hibitors (Antibiotics): Delvotest® SP – DSM Food Specialties, controls abandoned dairy farming (high number of dairy REVELLI, G.R.1; SBODIO, O.A.2; TERCERO, E.J.2

RIA / Vol. 37 / N.À 2 Figure 1. Evolution of the total number of dairy farms and samples tested in the period 1993-2009.
farms were closed between 2007 and 2009) whilst others The analysis of Table 1 shows acidity and pH levels at decided to undertake other activities such as crop farming 16.30 ± 0.96 °D and 6.68 ± 0.04, respectively, which are and husbandry. As a result of lack of foresight and clear go- normal values as indicated by Walstra and Jenness vernment policies in addition to an important climatic factor (1984) and the Argentine Food Code (2006). Average in recent years (2007-2009 drought which was the worst in content of milk fat was 3.48 ± 0.24% which is slightly the past 50 years) a great number of dairy farmers in the re- above the standard used as a reference by SanCor Co- gion went into bankruptcy.
operativas Unidas Ltda. to pay the farmers (3.47%).
Average content of true protein was 3.11 ± 0.12% which GENERAL COMPOSITION OF RAW MILK, PERIOD
compared well with the values reported by Sbodio et al. (1999a) and is significant since most of the production isintended for the cheese industry. Average content of lac- The physicochemical, microbiological and health quality tose (4.74 ± 0.16) was considered acceptable and a re- indicators (number of samples, mean value, standard de- ference. Although results for ash content were normal viation, confidence interval, minimum and maximum values) (0.70 ± 0.09%) it is important to note that data from stu- of milk from the 55 farms included in the study between dies performed in the area by Sbodio et al. (1999b) ge- 1993 and 2009 are shown in Table 1. nerated concern as they indicated high levels of sodium Table 1. Quality indicators for milk from dairy farms tested by the "Laboratorio Integral de Servicios Analíticos" (L.I.S.A.) in the period
1993-2009.
Study and evolution of the quality of raw milk from dairy farms in the northwest of the province of Santa Fe and south. August 2011, Argentina and chlorides as well as a very low level of potassium cell count, ≤ 300,000 SC/ml, between 82 and 47% of the total This indicator has varied significantly and seems to be milk currently produced could be in this category. increasing in recent years. Total solids averaged 12.18 ±0.42% indicating an acceptable physicochemical compo- Antibiotic residues in raw milk collected from bulk tank sition of the milk from the region. Values for cryoscopic from the 55 dairy farms studied were very low (0.36% Posi- descent were normal at -0.530 ± 0.02 °C and substan- tive, 19 cases). No antimicrobial residues were found in the tially below those found by Sbodio et al. (1997) although remaining 5,215 samples tested. These values are signifi- problems were identified in some water points where the cantly lower than those reported by Revelli et al. (2007) in a value was -0.409 °C. Results for average bacteria count study between 1993 and 2002 that involved the same farms and somatic cell count were 9.6 x 104 ± 2.2 x 105 CFU/ml that found 0.80% positive samples. Promotion of a contro- and 407,000 ± 230,000 SC/ml, respectively, indicating an lled and rational use of antibiotics, fostering of training both acceptable microbiological and health quality of the milk for agricultural and dairy farmers, particularly in treatment from the region particularly considering the duration of and prevention of intramammary diseases, contributed to the study and that in the early 1990s hygiene and health produce 99.64% of the milk free of contaminants. information and its use to determine the amount paid to During the period of the experiment, accidental cases in farmers was almost nonexistent. SanCor Cooperativas which presence of antibiotics in milk was presumed as a result Unidas Ltda. required health checks based on somatic of errors in milking routines, deficient identification of treated cell count in 2000 and at that time established that the animals and cows under drying treatment that had an earlier acceptable limit for premium milk quality was 600,000 calving date were analyzed and showed that 60% of the test results were positive. Reporting these accidents in time avoi-ded more contamination and penalties from the industry. This undoubtedly is very important because the penalties applied by the industry for not meeting the required indices EVOLUTION OF THE PHYSICOCHEMICAL, MICRO-
are very high (between 10 to 40%) and substantially reduce BIOLOGICAL AND HEALTH PARAMETERS ANALYZED
the price paid to farmers for the milk. Furthermore, consideringthat an additional 4% over the base price is paid for premium The annual evolution of the selected indicators in the pe- milk ("Leche Plus") determined as having microbiological qua- riod 1993 and 2009, including the corresponding equations lity ≤ 5.0 x 104 CFU/ml and teat health, monitored by somatic and polynomial trend lines, are shown in Figure 2. REVELLI, G.R.1; SBODIO, O.A.2; TERCERO, E.J.2 RIA / Vol. 37 / N.À 2 Figure 2. Evolution of pH, milk fat, true protein, lactose, ash, total solids, cryoscopic descent, total bacteria count and somatic cell count
expressed as an average of total annual tests performed in the period 1993-2009.
After analyzing Figure 2 we conclude that the physicoche- Acidity and pH results dropped from 18.83 to 15.13ºD mical, microbiological and health parameters reviewed over and from 6.65 to 6.68, respectively, indicating improve- the 17 years of the study improved significantly. ments in hygiene and storage, particularly as until 1996some farms delivered non-refrigerated milk. This situation Analytical results for some indicators are discontinuous changed in 1997 when all farms installed chillers. Particu- because over the years the laboratory adopted new techni- larly as of 1995, values tested for milk fat and true protein ques and not all tests were routinely performed.
showed a significant increase reaching maximum peaks of Study and evolution of the quality of raw milk from dairy farms in the northwest of the province of Santa Fe and south. August 2011, Argentina 3.60% and 3.14% for milk fat in 2009 and for true protein in Total bacteria counts varied between 3.2 x 105 CFU/ml 2003, 2005 and 2007. Clearly this significant improvement (1993) and 2.5 x 104 CFU/ml (2009) reflecting corrections in is the result of continuous genetic improvement and more hygiene and storage, particularly taking into account that efficient nutritional management regarding which the fee- until 1996 some farms delivered non-refrigerated milk. In ding of supplements and concentrates throughout the year 2009, a slight increase (2.5 x 105 CFU/ml) was observed be- is important. Total rainfall in 1998 was 1,100 mm. This cau- cause the industry required all milk to be delivered refrige- sed floods in the area and variations in some indicators, in rated and the few dairy farms that did not have this particular, a significant increase in acidity (17.13 °D), a equipment were forced to purchase one although the results sharp drop in pH (6.66) and lower levels of milk fat (3.40%) were not immediately optimized. As of 1999, the levels ob- which should be at attributed to hygiene, health and nutri- served were significantly lower than the findings of the study tional conditions resulting from inadequate milking, flooding conducted by Taverna et al. (2001b) which characterized the of roads, problems with milk collection systems and loss of dairy farms in the Central Milk Basin of Argentina and de- almost all pastures. Oppositely, that same year, the true termined values of 7.4 x 104 CFU/ml (geometric average) protein indicator reached one of the highest levels (3.13%) and bacteria count in 66% of all the milk tested (1,119,296 in the 17 years of the study due to the high volume of sup- l) below 1.0 x 105 CFU/ml.
plements added to the diet to maintain production levels.
However, testing of the proteolytic activity, plasmin/plas- The highest peak for lactose (4.80%) which led to an incre- minogen system and microbial contamination in the area ase in the number of liters produced occurred in 2000 due showed that casein deterioration in samples of lower quality to nutritional issues. However, in 2009 this indicator drop- milk was still significant (Sbodio et al., 1999a).
ped to the lowest level (4.63%) in the last 10 years of thestudy because of the drought that affected the area which In our opinion, improvement of health aspects, particularly not only had a negative impact on the liters of milk produced mastitis control, including work routines, checking of milking but almost depleted the pastures and resulted in a negative equipment, teat dipping, drying treatment, treatment of cli- cost/benefit ratio of grain supplementation of the diet. The nical cases, culling of cows with chronic condition and par- initial diagnosis of ash content in 1993 was, on average, ticularly, quality control of inputs, contributed to the 0.70% which is similar to the values reported by Taverna et significant decrease in average content of somatic cells al. (2001d) in the Central Milk Basin of Argentina. A com- which dropped from 687,000 SC/ml in 1993 to 423,000 parison of these results with current data (2009) showed an SC/ml in 2009. As of 1995, levels dropped significantly rea- 0.03% increase which is in line with historical data indica- ching levels similar to those found by Taverna et al. (2001b) ting high levels of sodium and chlorides in the area. The li- who reported a value, expressed as a geometric average, mitations this causes are known because it modifies the of 407,000 SC/ml and a count below 400,000 SC/ml in 53% organoleptic characteristics of the end product which ac- of all the milk tested (909,139 l). The flood in 1998 caused quires a strong salty taste that precludes selling to markets an increase (491,000 SC/ml) in SCC which is attributed to that are sensitive to these properties (Tercero et al., 1993).
hygiene and health issues resulting from inadequate milking Average content of total solids in 1993 was 11.52%. Com- conditions, flooding of roads and problems with the milk co- pared to the year in which the highest increase was obser- llection system, among others. ved (12.43% in 2007) there was an 8% increase due tothe significant higher values for most of the indicators analy- Revelli and Rodríguez (2001) studied the prevalent cau- zed. We believe that the optimization of the production sative pathogens of bovine mastitis and their sensitivity to system, particularly of the genetic, nutritional and manage- the different chemicals used. Results for the area indicated ment resources enabled the achievement of these results.
a high incidence of Staphylococcus aureus (43%) strains The effect of the drought in 2007 and 2009 had a negative that were highly sensitive (≥ 95%) to most of the antibiotics impact on total solids which averaged between 12.43 and used. The study also reported a low prevalence of Strepto- 12.20%, respectively. Regarding cryoscopic descent, an im- coccus agalactiae (3%) and a high load of environmental portant trend towards stabilization was observed in the last contaminants originating mainly from the water used for five years with values reaching -0.528 °C and -0.523 °C in washing on the farm.
2005 and 2009, respectively, and which could be attributed Important to note is that over the 17 years of this study, to the corrective measures that were implemented on the actions to improve the management capacity and operatio- farms regarding sanitation of milking equipment, refrigera- nal quality of the dairy farms were implemented through tion equipment, maintenance of cooling plates and, espe- dynamic Training Programs that were of great importance cially, no water accumulation after washing of the milking and significantly contributed to the achieved results. circuit. In this regard, interesting to note is that mean cryos-copy values found in the area greatly exceeded the values included in the Argentine Food Code (2006) (maximum -0.512 ºC) wherefore establishment of regional values and The Chi-Square (χ²) Goodness of Fit Test shows normal normal variation margins for the different seasons of the distributions with a 90% confidence level (α = 0.1) for all the year given the differences in feeding systems and the ge- indicators that were analyzed. The correlations matrix for all netic potential of the dairy herds should be considered.
indicators evaluated in the study is included in Table 2. REVELLI, G.R.1; SBODIO, O.A.2; TERCERO, E.J.2

RIA / Vol. 37 / N.À 2 Table 2. Matrix of correlation coefficients for selected quality indicators for milk on the farms for the period 1993-2009.
The analysis of the matrix included in Table 2 shows that matic conditions including animal drinking water quality and of the 41 correlations studied by applying a simple linear re- health issues. Results indicated that of great significance gression model, most relevant correlations were: %MF vs were the improvement in the composition of the milk with a %TS (r = 0.784) (n = 2.593) and %TP vs %TS (r = 0.557) (n significant increase in the content of fat, protein and total so- = 2.593), both being significant for P < 0.001. Of importance lids and a significant drop in total bacteria and somatic cell was the low correlation between %MF vs %TP (r = 0.261) counts. Undoubtedly this effective tool helped farmers in the (n = 10,188) (P < 0.001) which is consistent with the frequent area to respond to the requirements of the industry and ob- inversion in milk fat and true protein values observed mainly tain the maximum economic benefit for their production. in the spring and is attributed to imbalances caused by theadministration of diets having excess quantities of protein In our opinion, these efforts and results should be brought and insufficient energy (Gallardo, 2003). From the nutritional together for the farmers to have higher economic returns viewpoint, the need to formulate diets that are balanced in with sustainable development of the dairy farms in the re- energy content, including supplements or silage to achieve gion. We are also convinced that food health authorities a balance of the pasture whilst minimizing the effect of dif- should increase controls through a continuous, rigorous and ferent conditioning factors such as mastitis, heat stress, drin- efficient inspection system to improve not only the quality of king water quality and others that continue having a negative the raw material but also the infrastructure, equipment and effect in the production area is justified. environmental impact. More work is required, particularly inthe area of norms, animal health (brucellosis, tuberculosis Evidence of the quality of the water provided to the ani- and leukosis), quality of the drinking water provided to the mals in the area shows high levels of salinity, sulfate, total animals and lowering the incidence of mastitis whilst recog- hardness and nitrites which have a negative impact on pro- nizing that the farmers are at the center of the dairy produc- duction as well as on compositional and reproductive para- tion chain. We believe that the rules on prices paid by the meters (Revelli et al., 2002; 2005). Recent research with dairy plants should be known in advance and agreed jointly cows having high productive merit ( 32 l/cow/day) did not by the farmers, businessmen and the government. Coun- show these effects but rather the high capacity of the ani- tries that have a longer history in dairy farming and that im- mals to adapt to different drinking water quality due to the plemented this many decades ago are the best example buffer effect of the rumen (Valtorta et al. 2008). These re- because they produce more and better quality milk.
sults generated great concern as they indicate that waterquality is of the utmost importance and a critical factor that should be considered from a nutritional viewpoint.
This study was carried out within the framework of the "Mutual Cooperation Agreement" between the "LaboratorioIntegral de Servicios Analíticos" (L.I.S.A.) of the "Coopera- tiva Tambera y Agropecuaria Nueva Alpina Ltda." and theFood Technology Institute (I.T.A.) of the School of Chemical Improvements in the diet, management routines and ani- Engineering, National University of Littoral. mal genetics together with a comprehensive milk quality ma-nagement system allows the production of high quality milk The authors wish to especially thank the Administration even in rigorous environments, particularly as regards cli- Council of the "Cooperativa Tambera y Agropecuaria Nueva Study and evolution of the quality of raw milk from dairy farms in the northwest of the province of Santa Fe and south. August 2011, Argentina Alpina Ltda." and all its members for having implemented clear MARTH, E. 1981. Assuring the quality of milk. J. Dairy Sci. 64, quality policies, stimulated and continuously strengthened co- operative growth and development over these 17 years. MELO, O. 2005. Ganadería chaqueña / Ganadería pampeana: ¿iguales o diferentes?. Publicación "Forrajes 2005 Córdoba. Po-tenciando el desarrollo ganadero sustentable del subtrópico Ar-gentino". pp. 142-152.
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Study and evolution of the quality of raw milk from dairy farms in the northwest of the province of Santa Fe and south.

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