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The aim of this study was to quantify some environmental (individual herds, herd productivity, milking system, and season) and animal factors [individual animals, breed, days in milk (DIM) and parity] on the variability of the log-10 transformation of somatic cell count (LSCC) and differential somatic cell count (DSCC) on individual bovine milk. A total of 159,360 test-day records related to milk production and composition were extracted from 12,849 Holstein-Friesian and 9,275 Simmental cows distributed across 223 herds. Herds were classified into high and low productivity, defined according to the average daily milk net energy output (DMEO) yielded by the cows. Data included daily milk yield (DYM; kg/d), milk fat, protein, lactose, SCC, and DSCC, and information on herds (i.e., productivity, milking system). The daily production of total and differential somatic cells in milk was calculated and then log-10 transformed, obtaining DLSCC and DLDSCC, respectively. Data were analyzed using a mixed model including the effects of individual herd, animal, repeated measurements intra animal as random, and herd productivity, milking system, season, breed, DIM, parity, DIM × parity, breed × season, DIM × milking system and parity × milking system as fixed factors. Herds with a high DMEO were characterized by a lower content of LSCC and DSCC, and higher DLSCC and DLDSCC, compared to the low DMEO herds. The association between milking system and somatic cell traits suggested that the use of the automatic milking systems would not allow for a rapid intervention on the cow, as evidenced by the higher content of all somatic cell traits compared to the other milking systems. Season was an important source of variation, as evidenced by high LSCC and DSCC content in milk during summer. Breed of cow had a large influence, with Holstein-Friesian having greater LSCC, DSCC, DLSCC, and DLDSCC compared to Simmental. With regard to DIM, the variability of LSCC was mostly related to that of DSCC, showing an increase from calving to the end of lactation, and suggesting the higher occurrence of chronic mastitis in cows toward the end of lactation. All the somatic cell traits increased across number of parities, possibly because older cows may have increased susceptibility to intramammary infections.

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.

A pecuária de corte é uma das atividades mais importantes do setor agropecuário brasileiro, pois além de ser um segmento econômico existente em todo o território nacional emprega milhões de. O país possui o maior rebanho comercial de bovinos do mundo. A maior parte desses animais é criada em pastagens, que ocupam em torno de 20% do território brasileiro ou o equivalente a 3 vezes a área cultivada pelas principais culturas agrícolas (café, laranja, soja, milho, arroz, algodão, etc). No Acre, a pecuária bovina vem passando por grandes transformações. O processo acelerado de ampliação das áreas de pastagens e do rebanho, ocorrido na década de setenta, está sendo substituído pelo investimento em tecnologias que ajudem a melhorar a produtividade. As cadeias produtivas de corte e leite estão entre as atividades econômicas mais rentáveis do Estado, e dispõem de grande potencial para se destacar pela qualidade de seus produtos. Foi simulada uma população base contento mil matrizes e suas parições de acordo com os índices zootécnicos de uma típica propriedade de gado de corte na fase de cria. As médias e herdabilidades simuladas foram obtidas de diversos estudos em situações reais de rebanhos de cria brasileiros. Os índices de seleção adotados neste trabalho resultaram em ganhos genéticos favoráveis e podem ser inseridos em planos de melhoramento genético em rebanhos de corte no Acre. Diferentes índices de seleção resultam em diferentes classificações de touros. A utilização de índices de seleção maternos para descarte técnicos de vacas contribui para melhoria dos ganhos genéticos ao longo das gerações. Made available in DSpace on 2018-01-24T22:12:38Z (GMT). No. of bitstreams: 1 26493.pdf: 857926 bytes, checksum: e454f4b43ae8008c9eb604f648ae543d (MD5) Previous issue date: 2018-01-23 Dissertação (Mestrado em Ciências e Inovação Tecnológica) - Programa de Pós-graduação em Ciência, Inovação e Tecnologia para a Amazônia, Universidade Federal do Acre, Rio Branco. Orientador: Orientador: Fábio Augusto Gomes. Co-orientador: José Marques Carneiro Júnior.

Milk coagulation properties (MCP) have been widely investigated in the past using milk collected from different cattle breeds and herds. However, to our knowledge, no previous studies have assessed MCP in individual milk samples from several multi-breed herds characterized by either high or low milk productivity, thereby allowing the effects of herd and cow breed to be evaluated independently. Multi-breed herds (n=41) were classified into 2 categories based on milk productivity (high vs. low), defined according to the average milk net energy yielded daily by lactating cows. Milk samples were taken from 1,508 cows of 6 different breeds: 3 specialized dairy (Holstein-Friesian, Brown Swiss, Jersey) and 3 dual-purpose (Simmental, Rendena, Alpine Grey) breeds, and analyzed in duplicate (3,016 tests) using 2 lactodynamographs to obtain 240 curd firming (CF) measurements over 60min (1 every 15 s) for each duplicate. The 5 traditional single-point MCP (RCT, k 20 , a 30 , a 45 , and a 60 ) were yielded directly by the instrument from the available CF measures. All 240 CF measures of each replicate were also used to estimate 4 individual equation parameters: RCT estimated according to curd firm change over time modeling (RCT eq ), asymptotic potential curd firmness (CF P ), curd firming instant rate constant (k CF ), and syneresis instant rate constant (k SR ) and 2 derived traits: maximum curd firmness achieved within 45min (CF max ) and time at achievement of CF max (t max ) by curvilinear regression using a nonlinear procedure. Results showed that the effect of herd-date on traditional and modeled MCP was modest, ranging from 6.1% of total variance for k 20 to 10.7% for RCT, whereas individual animal variance was the highest, ranging from 32.0% for t max to 82.5% for RCT eq . The repeatability of MCP was high (>80%) for all traits except those associated with the last part of the lactodynamographic curve (i.e., a 60 , k SR , k CF , and t max : 57 to 71%). Reproducibility, taking into account the effect of instrument, was equal to or slightly lower than repeatability. Milk samples collected in farms characterized by high productivity exhibited delayed coagulation (RCT eq : 18.6 vs. 16.3min) but greater potential curd firmness (CF P : 76.8 vs. 71.9mm) compared with milk samples collected from low-productivity herds. Parity and days in milk influenced almost all MCP. Large differences in all MCP traits were observed among breeds, both between specialized and dual-purpose breeds and within these 2 groups of breeds, even after adjusting for milk quality and yield. Milk quality and MCP of samples from Jersey cows, and coagulation time of samples from Rendena cows were better than in milk from Holstein-Friesian cows, and intermediate results were found with the other breeds of Alpine origin. The results of this study, taking into account the intrinsic limitation of this technique, show that the effects of breed on traditional and modeled MCP are much greater than the effects of herd productivity class, parity, and DIM. Moreover, the variance in individual animals is much greater than the variance in individual herds within herd productivity class. It seems that improvement in MCP depends more on genetics (e.g., breed, selection) than on environmental and management factors.

Caribou (Rangifer tarandus granti) calf:cow ratios (CCR) computed from composition counts obtained on arctic calving grounds are biased estimators of net calf production (NCP, the product of parturition rate and early calf survival) for sexually-mature females. Sexually-immature 2-year-old females, which are indistinguishable from sexually-mature females without calves, are included in the denominator, thereby biasing the calculated ratio low. This underestimate increases with the proportion of 2-year-old females in the population. We estimated the magnitude of this error with deterministic simulations under three scenarios of calf and yearling annual survival (respectively: low, 60 and 70%; medium, 70 and 80%; high, 80 and 90%) for five levels of unbiased NCP: 20, 40, 60, 80, and 100%. We assumed a survival rate of 90% for both 2-year-old and mature females. For each NCP, we computed numbers of 2-year-old females surviving annually and increased the denominator of CCR accordingly. We then calculated a series of hypothetical “observed” CCRs, which stabilized during the last 6 years of the simulations, and documented the degree to which each 6-year mean CCR differed from the corresponding NCP. For the three calf and yearling survival scenarios, proportional underestimates of NCP by CCR ranged 0.046–0.156, 0.058–0.187, and 0.071–0.216, respectively. Unfortunately, because parturition and survival rates are typically variable (i.e., age distribution is unstable), the magnitude of the error is not predictable without substantial supporting information. We recommend maintaining a sufficient sample of known-age radiocollared females in each herd and implementing a regular relocation schedule during the calving period to obtain unbiased estimates of both parturition rate and NCP.