Lactating dairy cows convert 25 to 35% of intake N to milk N, and a part of the remaining N ends up in the environment, causing pollution. Dairy cows absorb amino acids available in the small intestine supplied mainly by digestion of microbial protein and ruminally undegraded feed protein (RUP). Ruminally degradable feed protein (RDP) is the major supplier of N for microbial protein synthesis. Most of the excess RDP will be degraded to ammonia and eliminated as urea in urine. Thus, avoiding excess RDP in dairy cattle diets is important in reducing environmental N pollution. The objectives of the work in this dissertation were to test the hypothesis that lactating dairy cows, when fed varying dietary RDP, can maintain feed intake, milk and milk protein yield, ruminal metabolism, passage of nutrients out of the rumen, and N excretion. The first study investigated the effects of decreasing RDP in lactating dairy cow diets on feed intake, milk production and apparent N efficiency. Forty mid-lactation cows (36 Holstein and 4 Jersey × Holstein cross-breds) were fed a diet containing 11.3% of diet dry matter (DM) as RDP for the first 28 d (covariate period). From d 29 to 47 (treatment period) cows were randomly assigned to 1 of 4 diets containing constant RUP (7.1% of DM) but 11.3, 10.1, 8.8, or 7.6% of DM as RDP. Reducing RDP in diets linearly decreased DM intake and tended to decrease milk yield. Milk protein, fat and lactose contents, milk protein yield, body weight, and plasma essential amino acids were unaffected by reduced dietary RDP. However, milk urea-N concentration and milk fat yield decreased linearly with reduced dietary RDP. The apparent efficiency of N utilization for milk N production increased linearly as dietary RDP was reduced. As RDP declined in diets, linear reductions in DM intake and milk production suggested that these cannot be maintained below NRC recommendations of RDP for cows in this study. The aim of the second study was to test the hypothesis that decreasing dietary RDP in lactating dairy cow diets can maintain ruminal metabolism and flow of nutrients out of the rumen and reduce nitrogen excretion. This study was designed as a replicated Latin square with 4 periods of 21 d each. Four treatment diets containing decreasing RDP and constant RUP similar to the first study were used. Three ruminally and duodenally cannulated and 4 ruminally cannulated lactating Holstein cows were randomly assigned to one of the four dietary treatments. A double marker system with Co-EDTA and Yb-labeled forage as markers was used to determine ruminal outflows of nutrients from omasal samples and nutrients reaching the intestine from duodenal samples. Ruminal microbial protein flow was observed using ¹⁵N as an external microbial marker. Feed intake, milk yield, milk composition, and urine and feces output were determined in the last week of each period. Ruminal fluid samples were taken 2 and 4 h after feeding to determine ruminal NH₃-N and volatile fatty acid concentrations. Outflows of nutrients from the rumen were determined by analyzing omasal samples collected over a 24 h feeding cycle in the last week of each period. Reducing dietary RDP decreased protein intakes while DM and fiber intakes were unaffected. Ruminal NH₃-N concentrations linearly declined and peptides and amino acids were unaffected with reduced dietary RDP. A trend for a linear decline in ruminal outflows of microbial N and total N was observed with decreasing dietary RDP. Ruminal volatile fatty acids concentrations were unaltered by feeding treatment diets. Ruminal outflows of DM and acid detergent and neutral detergent fibers were unaffected by treatments. Treatment diets did not have any effect on milk yield and milk composition. However, milk urea-N and milk fat yield decreased linearly with decreasing dietary RDP. Reducing dietary RDP did not affect milk and milk protein yields but did result in greater body protein mobilization. Fecal N output was unaffected however, urine volume and urine N output decreased linearly suggesting reduced environmental N pollution. There was a trend for a linear decrease in total body N balance, but no significant effects on calculated ruminal N balance as dietary RDP decreased. Linear reductions in microbial N leaving the rumen were due to decreased ruminal NH₃-N as peptides plus amino acids and energy supply were unaffected. The linear reduction in milk production and microbial N flow in the first and second studies, respectively, did not support our hypothesis that lactating dairy cows can be fed dietary RDP below current NRC (2001) recommendations without affecting animal performance. The need to raise 15% more cows to alleviate the loss in production may nullify the advantage in reduced N output into the environment by cows fed lower dietary RDP. / Ph. D.

Chapters 2 and 3 are the peer reviewed version of the following articles, respectively: Anzai H, Wang L, Oishi K, Irbis C, Li K, Kumagai H, Inamura T, Hirooka H. 2015. Estimation of nitrogen and phosphorus flows in livestock production in Dianchi Lake basin, China. Animal Science Journal. Amachika Y, Anzai H, Wang L, Oishi K, Irbis C, Li K, Kumagai H, Inamura T, Hirooka, H. 2015. Estimation of potassium and magnesium flows in animal production in Dianchi Lake basin, China. Animal Science Journal. , which have been published in final forms at http://dx.doi.org/10.1111/asj.12390 and http://dx.doi.org/10.1111/asj.12518, respectively These articles may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Chapter 4 is the peer reviewed version of the following article: Anzai H, Oishi K, Li K, Irbis C, Hirooka H, Inamura T, Kumagai H. 2011. Dietary nitrate loads on cows in dairy farms near Lake Dian, Kunming city, Yunnan Province, China. Trace Nutrient Research 28, 54-57., which has been published in final form at http://www.jtnrs.com/sym28/P-07.pdf. / 京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19768号 / 農博第2164号 / 新制||農||1040(附属図書館) / 学位論文||H28||N4984(農学部図書室) / 32804 / 京都大学大学院農学研究科応用生物科学専攻 / (主査)教授 廣岡 博之, 教授 松井 徹, 教授 稲村 達也 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Two studies were conducted to evaluate the effects of varying dietary sources of rumen available carbohydrate (RAC) and rumen available protein (RAP) on milk yield and milk composition, nutrient flow to the duodenum, ruminal and total tract nutrient digestibilities, and ruminal pH, ammonia-N, and VFA concentrations in lactating cows. The first study was a response surface design utilizing nine dietary combinations of RAC and RAP. The response surfaces of all milk variables were saddle-shaped. Because of the saddle-shaped surfaces, an optimum combination of RAP and RAC for milk production variables was not obvious from the limited range of RAC and RAP used in this study. Ridge analysis of the saddle surfaces predicted maximum milk yield when dietary RAC was below 69 % of the DM and RAP below 60% of CP in alfalfa-corn silage based diets. In the second study, four cannulated (ruminal and duodenal) cows were utilized in a 4x4 Latin square design. Four of the nine original diets were selected to provide the largest range of RAC and RAP. Nutrient flow, digestiblities and ruminal parameters were evaluated. Although the in situ incubations indicated that rates of DM, CP, and NDF degradabilities differed among diets, no effects on overall ruminal pH and total VFA concentrations were detected. Additionally, DM, OM, NDF, ADF, and N flows to the duodenum were not affected by dietary treatment. Nonmicrobial N flow was greater for the barley-based diet, yet microbial flow was not different. The differences in rates of availability determined by in situ methods were not large enough to illicit a measurable difference in nutrient digestion and utilization. Additionally, the data implied that none of the diets were limiting in RAC and RAP for vigorous microbial activity. Fat-corrected (3.5%) milk production was greatest (P<.05) when alfalfa-corn silage based diets contained supplements providing intermediate (69 % RAe) carbohydrate availability (corn and barley) and low (60 % RAP) ruminal protein availability (BM and SBM). The increase in fat-corrected milk was consistent with the predicted milk production response in the previous study when RAP exceeded 62% of CP. However, the ruminal parameters, nutrient flow, and nutrient digestibility measurements did not adequately explain the increased milk production when diets contained increased concentrations of BM. / Ph. D.

Die Nutztierhaltung in Nordwestdeutschland befindet sich derzeit in dem empfindlichen Dilemma zwischen den wirtschaftliche Erfordernissen, welche der internationale Strukturwandel in der Nutztierhaltung an die Wettbewerbsfähigkeit stellt, und den derzeitigen Entwicklungspotentialen in der Region. Zum einen begrenzen die natürlichen Potentiale eine weiter ansteigende räumliche Verdichtung der Nutztierhaltung. Des Weiteren hat sich das gesellschaftliche Anforderungspotential an die Landwirtschaft als auch an den ländlichen Raum geändert und forciert keinen weiteren Anstieg der Nutztierhaltung. Die Bedingungen durch die hohe Tierdichte verlangen zunehmend, dass in Nordwestdeutschland eine nachhaltige Ausrichtung der Nutztierhaltung in höherem Maße verankert wird. Die vorliegende Arbeit beschreibt hierfür wesentliche Herausforderungen der Nutztierhaltung in den Bereichen Umweltschutz, der Tiergerechtheit intensiver Haltungssysteme und regionale Ressourcenkonflikte. Umweltschutz: Die Stoffdynamik von Stickstoff (N) und Phosphor (P) sämtlicher Betriebsgüter wurde auf sechs intensiven schweinehaltenden Betrieben über einen Zeitraum von 5 Jahren analysiert. Es wurde deutlich, dass die hohe Leistung und die leistungsbezogene Fütterung sich positiv auf Nährstoffeffizienz in der Tierhaltung auswirken, im Pflanzenbau jedoch Defizite bestehen. Insbesondere die Wahrnehmung der anfallenden Menge tierischer Exkremente als (N, P) Dünger ist unzureichend. Die Düngewirkung des Wirtschaftsdüngers [Unterschätzung N = 7,6 % (10,6 kg/ha), P = 33,6 % (11,6 kg/ha)], aber auch die Anwendung von Mineraldünger [N um 4,1 % (8,1 kg/ha), P um 12,7 % (1,5 kg/ha)] wurden deutlich unterschätzt. Als Folge hatten die Betriebe große Nährstoffverluste (104,5 kg N/ha; 11,7 kg P/ha) zu verzeichnen. Die Studie bewertet die kritischen Aspekte des Nährstoff-Managements und diskutiert mögliche Verbesserungen für die Zukunft. Tiergerechtheit intensiver Haltungssysteme: Auf drei Mastbetrieben intensiver Haltungsformen wurden jeweils sechs Analysen (wöchentlich) mit dem Bewertungssystem nach Welfare Quality® durchgeführt, um aufzuzeigen, inwiefern dieses geeignet ist, die Tiergerechtheit in intensiven Haltungssystemen zu analysieren. Es wird die Durchführbarkeit des Systems bewertet und analysiert, welche Rückschlüsse sich durch die Bewertung auf die Tiergerechtheit intensiver Haltungsformen ziehen lassen. In der Gesamtbewertung (excellent, enhanced, acceptable or not classified) wurden 72,3 % aller Untersuchungen der zweiten Bewertungskategorie "enhanced" zugeordnet, während 27,7 % die dritte Kategorie 7. Zusammenfassung 79 "akzeptabel" erreichten. Die Hauptkritikpunkte waren eine unzureichende Wasserversorgung, vorhandene Schleimbeutelentzündungen durch die Besatzdichte und das Ausleben natürlicher Verhaltensweisen. Die Untersuchung zeigt, dass das Bewertungssystem grundsätzlich geeignet ist, die Tiergerechtheit in intensiven Haltungssystemen zu analysieren, jedoch scheinen nicht alle Messungen (insbesondere im Bereich „Good Housing“ und „Good Health“) empfindlich genug zu sein, um Unterschiede der Tiergerechtheit zwischen intensiven Haltungssystemen in ausreichendem Maße bewerten zu können. Weitere Analysen mit einer größeren Anzahl von Betrieben sind hier nötig. Die Arbeit diskutiert mögliche Ansatzpunkte für die Verbesserung der Tiergerechtheit intensiver Haltungssysteme und greift hierbei auch die derzeitige gesellschaftliche Diskussion auf. Wachsende Konkurrenz um begrenzte regionale Ressourcen: Die Studie stellt dar, welche Anreizmechanismen und Konflikte die Nutztierhalter als regionale Indikatoren für die Zukunftsfähigkeit des Standortes wahrnehmen. Auf Grundlage der theoretischen Erklärungsansätze für Auswirkungen von intensiven Tierhaltungsregionen ist ein Fragebogen konzipiert worden, welcher in Form einer Onlinebefragung bei 137 Landwirten in der gesamten Region Nordwestdeutschlands durchgeführt wurde. Es wird deutlich, dass sich die Nutztierhaltung, mit den regionalen Herausforderungen einer zunehmend verdichteten Tierhaltung deutlicher konfrontiert sieht, als vorteilhafte Produktionsbedingung wahrgenommen werden. Als bedeutende Ressourcenkonflikte sind eine ansteigende Flächenknappheit für die Verwertung des Wirtschaftsdüngers, die Anforderungen durch den Natur- und Landschaftsschutz als auch eine ansteigende Standortproblematik für Bauvorhaben ausschlaggebend. Im Gegensatz zu dieser hohen Wahrnehmung negativer Auswirkungen des Produktionsstandortes in Nordwestdeutschland wird noch erhebliches Potential für weitere Erweiterungsmöglichkeiten der Tierbestände in Nordwestdeutschland gesehen. Zugleich werden der intensiven Tierhaltung in Nordwestdeutschland auch bedeutende vorteilhafte Produktionsbedingungen zugesprochen. Die Nutzeffekte werden vor allem im human- und social-Kapital gesehen werden. Diese Elemente verursachen jedoch ebenso ein geringes geografisches Reaktionsvermögen auf die zunehmenden Problemstellungen und lassen die Raumnutzungskonflikte weiter ansteigen. Durch die Wahrnehmung der Standortauswirkungen trägt die Arbeit dazu bei, die Anforderungen der Nutztierhalter an die Produktionsbedingungen in der Regionalentwicklung stärker zu berücksichtigen und bestehenden Problemstellungen entgegenzuwirken.

A series of experiments were conducted to determine nutritional strategies to improve the efficiency of N utilization in dairy cows when feeding co-products including wheat-based (W-DDGS) and corn-wheat blend distillers grains with solubles (B-DDGS), and dried whey permeate (DWP). In Experiment 1, the objective was to determine the effects of replacing canola meal (CM) as the major protein source with W-DDGS on ruminal fermentation, microbial protein production, omasal nutrient flow, and animal performance. Cows were fed either a standard barley silage-based total mixed ration containing CM as the major protein supplement (0% W-DDGS, control) or diets formulated to contain 10, 15 and 20% W-DDGS (dry matter [DM] basis), with W-DDGS replacing primarily CM. Diets were isonitrogenous (18.9% crude protein [CP]). Inclusion of W-DDGS to the diet did not negatively affect ruminal fermentation, microbial protein production, and omasal nutrient flow. However, there was a 0.7- to 2.4-kg increase in DM intake, and a 1.2- to 1.8-kg increase in milk yield after the addition of W-DDGS in place of CM. In Experiment 2, the objective was to delineate the effects of including either W-DDGS or B-DDGS dried distillers grains with solubles as the major protein source in low or high CP diets fed to dairy cows on ruminal function, microbial protein synthesis, omasal nutrient flows, urea-N recycling, and milk production. The treatment factors were type of distillers co-product (W-DDGS vs. B-DDGS) and dietary CP content (15.2 vs. 17.3%; DM basis). The B-DDGS was produced from a mixture of 15% wheat and 85% corn grain. All diets were formulated to contain 10% W-DDGS or B-DDGS on a DM basis. Feeding up to 10% of dietary DM as B-DDGS or W-DDGS as the major source of protein did not have negative effects on metabolizable protein (MP) supply and milk production in dairy cows. However, reducing dietary CP content from 17.3 to 15.2% decreased milk production. This response was attributed to an insufficient supply of ruminally degradable protein (RDP) that suppressed microbial nonammonia N (NAN) synthesis in the rumen, thus decreasing intestinal MP supply. In Experiment 3, the objective was to determine the effects of replacing barley or corn starch with lactose (as DWP) in diets containing 10% W-DDGS on ruminal function, omasal nutrient flow, and lactation performance. The treatment factors were source of starch (barley vs. corn) and dietary inclusion level of DWP (0 vs. 6%; DM basis) as a partial replacement for starch. Diets were isonitrogenous (18% CP) and contained 3 or 8% total sugar. The starch content of the low sugar diet was 24% compared to 20% for the high sugar diet. Dry matter intake, and milk and milk component yields did not differ with diet. However, partially replacing dietary corn or barley starch with sugar up-regulated ruminal acetate and propionate absorption, and reduced ruminal NH3-N concentration, but had no effect on ruminal pH, microbial protein synthesis, omasal nutrient flow and production in dairy cows. In summary, data presented in this thesis indicate that W-DDGS and B-DDGS can be included as the major source of protein in dairy cow diets without compromising ruminal function, nutrient supply and milk production in dairy cows. Feeding medium to low CP diets, and partial replacement of starch with sugar in diets containing W-DDGS and B-DDGS can improve N utilization efficiency in dairy cows. Additionally, an upregulation of facilitated transport of acetate and propionate across epithelial cells possibly prevents the occurrence of ruminal acidosis when lactose partially replaces starch in cow diets.