Stearns County, Minnesota is the number-one dairy-producing county in the number-one dairy-producing region--the Midwest--in the country. The area has been home to German-Catholic immigrants from the Rheinland region of Germany since the mid- to late-1850s, when they traveled across Canada and the northeastern United States before finally settling on homesteads in Central Minnesota. 150 years later, the descendants of these settlers still live and farm the same area. Through it all, these farmers have kept a similar schedule: six days of fieldwork, Sunday for rest. And, nearly since the day they arrived in the area, that day of rest has featured one sacred leisure activity: baseball. The state of Minnesota boasts over 250 amateur baseball teams, the most of any state in the country. In the summer of 2012, I moved to Spring Hill, Minnesota, a town of 85, to play for the Spring Hill Chargers and work on the farm. My thesis lies at the intersection of farming and baseball, showing the reader both how little and how much has changed for these men who still farm their land of their forebears and still play America's game. A Summer in the Land of Milk tells my story of living and working in a rural area where the past hangs like a shadow and the future is frighteningly uncertain.

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Understanding the particularities of pasture inclusion on cows' diets and their subsequent impact on the digestive processes, together with possible differences in the nutrient utilization of cows managed under grazing conditions, are challenges that must be elucidated in order to design strategies to improve the cows' productive performance. The objectives of this dissertation were: 1) to review the existing literature on ration formulation for dairy cows in pasture-based systems, identifying limitations and potential improvement areas, 2) to evaluate the adequacy of the Molly model predictions of ruminal fermentation, nutrient digestion, and performance from cows consuming fresh ryegrass-based diets, identifying mechanisms that could be used to direct further model improvements, 3) to evaluate the model predictions of milk, fat and protein production using data from Holstein-Friesian and Jersey cows from Chile managed under pasture-based systems, identifying mechanisms that could be used to direct further model improvements, 4) to identify the different dairy breeds and their crosses that are used in the Chilean dairy population, determining if there are specific breed and heterosis effects on productive and some functional traits, and 5) to characterize the ruminal degradation dynamics of crude protein (CP) and individual amino acids (AA) from ryegrass (Lolium perenne) at vegetative stage, generating information to improve the ration formulation in dairy cows in pasture-based systems. From the literature revision in objective 1, different factors that could help to create a more specific classification of dairy pasture-based systems were identified. Maximizing grass inclusion seems to leads to an oversimplification of diets, potentially limiting the performance of medium and high producing cows. Despite the low N use efficiencies reached in pasture-based systems, there is a lack of information in studies that delve into the ruminal degradation of CP and AA, as well as their intestinal absorption, and subsequent post-absorptive utilization. Advances in the understanding of these areas could help to create strategies to face this problem. There is evidence suggesting that cows can perform different under different productive systems, but various breeds, strains, and crossbreds are used in pasture-based systems, being needed first a better characterization of them. To achieve the second objective, a total of 25 studies (n = 115 treatments) including dairy cows consuming ryegrass predominant diets, published from 1970 through 2020, were collected from the literature and used to assess the model accuracy and precision based on root mean squared errors and concordance correlation coefficients (CCC). Predictions of protein and fiber digestion and fiber and organic matter fecal excretion were improved after model reparameterization, while body weight and body condition score predictions were improved after model modifications and reparameterization. Although digestion of nutrient was better represented by the new set of parameters derived, the accuracies of milk, protein, and fat production remained low (CCC of 0.13, 0.12, and 018, respectively), with moderate slope bias. To achieve the third objective, a dataset including 180 group cows' diets (153 from Holstein Friesian and 27 from Jersey cows) from 18 commercial dairy farms with different inclusion of ryegrass was compiled. Chemical composition of feeds ingredients, group intakes and animal performance records, were provided by the Chilean cooperative Colun. Separately model mammary reparameterization of Holstein Friesian and Jersey cows' data, improved both milk production (CCC values of 0.69 and 0.90, respectively) and milk solids predictions (CCC values of 0.68 and 0.92 for milk protein and 0.65 and 0.80 for milk fat, for Holstein Friesian and Jersey cows, respectively). This indicates that there seems to be some differences in mammary cells and cells activity between breeds evaluated, translated into different lactation curves and milk solids synthesis patters. To achieve the fourth objective, a dataset considering 1,429,132 records from 586,624 cows that calved between 1998 and 2018 was compiled. Pedigree information, milk, milk protein, and milk fat, as well as somatic cell score and calving interval records were provided by the Chilean cooperative COOPRINSEM. The proportion of each breed according to the different country origin (strain) was calculated for all the animals, being identified eight genetic strains with enough information to perform separated genetic evaluations: Chilean Friesian, French Holstein-Friesian, US-Holstein, US-Jersey, French Montbeliarde, New Zealander Holstein-Friesian, Swedish Red and White, and British Friesian. Four different genetic models, increasing in complexity (considering breed or strain classification, crossbreeding proportion, and heterosis effects) were tested. Specific effects for some genetic strains, as well as heterosis effects between some strains with Chilean Friesian were identified, so these effects should be considered when performing genetic evaluations in the Chilean dairy population. Also, they can be used to direct future selection programs. To achieve the last objective, an in situ study using three cannulated cows was carried out at the Agricultural Research Station of the Austral University of Chile (Valdivia, Chile). Samples from a perennial ryegrass pasture were collected during winter, spring and summer at vegetative stage. Duplicate bags were ruminally incubated for 4, 8, 12, 24, and 96 h. CP and AA profile of original samples and from incubation residues were determined. Ryegrass samples presented a high crude protein content (averaging 25.8%), however, the RUP content was ~15 to 20% of CP. Significant differences were observed for ryegrass CP and individual AA ruminal degradation kinetics, this seems to be associated to some specific AA. / Doctor of Philosophy / The used of pasture-based systems in dairy production are an important alternative in countries were local environmental and climatological conditions, as well as soil properties are suitable for the growth of high-quality grasslands. The main advantages attributed to the use of pasture-based system are the reduction in the production costs, and potentially improving the nutrition quality of dairy products as well as the cows' welfare. However, they have some important limitations as the natural variation in the quantity and quality of available herbage. Also, there is a lack of information on fundamental nutrition of pasture nutrients digestion and utilization by the cows manage and selected under these environmental conditions. The first two objectives of this dissertation consisted in using the Molly nutritional model, which represents the biology of the whole cow, in order to identify key aspects to better understand the cows manage under pasture-based systems and develop strategies to precise their nutrition. Particularly, topics such as prediction of ruminal fermentation and digestive processes, mobilization of body reserves, mammary glands metabolism, and potential differences between Holstein-Friesian and Jersey cows were analyzed. Overall, work on these objectives resulted in improvements to the Molly model for making predictions of diets that include grass. The diversity of breeds and their country of origin, as well as different crosses in the Chilean dairy population were explored. A more comprehensive genetic model was proposed in this work to precise the calculation of breeding values in the country. Furthermore, our findings could be used as inputs to direct future selection programs. The last objective explored the ruminal degradation of crude protein and each individual amino acid in ryegrass. We demonstrate that indeed there are differences in the degradation parameters for some amino acids. Due to the high degradability of fresh ryegrass, there could be some potential limitations in the supply of some essential amino acids, especially in high producing cows consuming predominant ryegrass diets.

Official type classification data recorded by the Holstein Friesian Association of America from January, 1967 to June, 1974 and DHIA production data recorded by the U.S. Department of Agriculture from January, 1960 to May, 1974 were evaluated as progeny tests to ascertain the relationship between body conformation and longevity and wearability of dairy cows. Data for 788 sires with at least 20 daughters in 10 herds with classification information and at least 30 daughters with production information was used. Means for type and production were daughter final score 80.1, predicted difference milk (PDM) -136, lifetime production 55,919 lb., production per day of productive life (PDL) 44A lb/day, age at last calving (AGE) 60. 1 mo., and percentage completing four lactations, 48.4%. Correlations between PDT and scorecard and descriptive traits were positive and highly significant (P < .01). Most of the relationships between PDM and type traits were negative and highly significant (P < .01) with the exception of dairy character which was positive ( .27). Longevity traits were lowly correlated with PDT and generally negative but were highly positively correlated with PDM. Correlations were low between longevity traits and descriptive and scorecard traits ranging from -.23 between PDL and rump to .21 between age and head. Regression of type and production traits on longevity traits indicated that PDM was the best predictor of LTP (R² = .28) and PCT 4 (R² = .12); however, the combined descriptive traits are the best predictor of PDL (R² = .12) and AGE (R² = .10). The best type indicators of longevity appeared to be dairy character, mammary system, udder quality, udder support and floor, teat site and placement, stature, fore udder, and rump. / Master of Science