title: The Breakdown of Skeletal Muscle in Dairy Cows During Peak Lactation

authors: Gray, Tarra Stacee

subjects: dairy cows

abstract: The decline in fertility in dairy cows is of international concern. Since 1950, milk production demands have increased while first service rates of conception have decreased. It is unclear why fertility has decreased, however current dairy management practice requires cows to be kept on a tight yearly calving schedule to ensure maximum milk production over the lifetime of the cow. The current postulate suggests that this regime places a high metabolic burden on the cows, which in turn requires the breakdown of tissues such as fat and muscle to provide substrates to meet the increased energy demands of lactation.

Immediately after calving, dairy cows enter a state of negative energy balance (EB), as they cannot consume enough energy to sustain lactation. During this period of negative EB, fat is mobilised in the form of non-esterified fatty acids to help supply the body with the extra energy it needs, but fat mobilisation decreases after four weeks while cows remain in a state of negative EB for several more weeks. It is unclear whether or not muscle breakdown occurs and plays a role in the restoration of EB in lactating cows during peak lactation. I hypothesized that the breakdown of muscle does occur in cows during peak lactation, and that it occurs to a greater extent in cows producing higher amounts of milk.

Dairy cows from three strains, NZL, NZH and OSH, representing cows with differing milk production abilities (low, intermediate and high, respectively), were studied for 12 weeks postpartum. Blood was drawn at weekly intervals and muscle biopsies taken at -1, 1, 4, 8, and 12 weeks postpartum.

Analysis of plasma revealed an increase in the abundance of troponin I-fs (a marker of muscle breakdown) over the period of study, suggesting that breakdown of skeletal muscle was occurring. Real-time polymerase chain reaction analysis showed that expression of the ubiquitin-proteasome (UbP) ligases atrogin-1 (atro1) and muscle ring finger protein 1 (murf1) increased initially, but returned to normal levels by four weeks postpartum. Concentration of mRNA of the lysosomal proteases, cathepsin B, D, H and L, did not change over the period of study. Therefore, the UbP pathway may contribute to the breakdown of muscle detected by troponin I-fs in plasma.

Proteins involved in translation initiation were examined by Western blotting. The ratio of phosphorylated over total eIF2alpha and 4E-BP1 remained unchanged throughout the study, indicating that the breakdown of muscle was not a result of decreased protein synthesis. However, there was a greater ratio of phosphorylated to total eIF2alpha in NZL cows compared with NZH and OSH, suggesting that protein synthesis was less overall in NZL cows than other strains. Measurement of myosin heavy chain composition indicated there was no change in the abundance of type I and type IIx muscle fibres and plasma myostatin levels did not change over the period of study. However, the OSH cows had less myostatin in their plasma than the NZL and NZH cows, suggesting that there may be inhibition of muscle growth occurring in this strain.

The results of this study suggest that breakdown of muscle could be important in restoring the EB in high-producing dairy cows during peak lactation. Upregulation of the UbP pathway during the first four weeks of lactation may contribute to this muscle breakdown. However, it remains unclear what processes then continue to regulate breakdown of skeletal muscle to maintain the elevated abundance of troponin I-fs in plasma from four to 12 weeks postpartum in lactating dairy cows.

text: The Breakdown of Skeletal Muscle in Dairy Cows During Peak Lactation The decline in fertility in dairy cows is of international concern. Since 1950, milk production demands have increased while first service rates of conception have decreased. It is unclear why fertility has decreased, however current dairy management practice requires cows to be kept on a tight yearly calving schedule to ensure maximum milk production over the lifetime of the cow. The current postulate suggests that this regime places a high metabolic burden on the cows, which in turn requires the breakdown of tissues such as fat and muscle to provide substrates to meet the increased energy demands of lactation.

Immediately after calving, dairy cows enter a state of negative energy balance (EB), as they cannot consume enough energy to sustain lactation. During this period of negative EB, fat is mobilised in the form of non-esterified fatty acids to help supply the body with the extra energy it needs, but fat mobilisation decreases after four weeks while cows remain in a state of negative EB for several more weeks. It is unclear whether or not muscle breakdown occurs and plays a role in the restoration of EB in lactating cows during peak lactation. I hypothesized that the breakdown of muscle does occur in cows during peak lactation, and that it occurs to a greater extent in cows producing higher amounts of milk.

Dairy cows from three strains, NZL, NZH and OSH, representing cows with differing milk production abilities (low, intermediate and high, respectively), were studied for 12 weeks postpartum. Blood was drawn at weekly intervals and muscle biopsies taken at -1, 1, 4, 8, and 12 weeks postpartum.

Analysis of plasma revealed an increase in the abundance of troponin I-fs (a marker of muscle breakdown) over the period of study, suggesting that breakdown of skeletal muscle was occurring. Real-time polymerase chain reaction analysis showed that expression of the ubiquitin-proteasome (UbP) ligases atrogin-1 (atro1) and muscle ring finger protein 1 (murf1) increased initially, but returned to normal levels by four weeks postpartum. Concentration of mRNA of the lysosomal proteases, cathepsin B, D, H and L, did not change over the period of study. Therefore, the UbP pathway may contribute to the breakdown of muscle detected by troponin I-fs in plasma.

Proteins involved in translation initiation were examined by Western blotting. The ratio of phosphorylated over total eIF2alpha and 4E-BP1 remained unchanged throughout the study, indicating that the breakdown of muscle was not a result of decreased protein synthesis. However, there was a greater ratio of phosphorylated to total eIF2alpha in NZL cows compared with NZH and OSH, suggesting that protein synthesis was less overall in NZL cows than other strains. Measurement of myosin heavy chain composition indicated there was no change in the abundance of type I and type IIx muscle fibres and plasma myostatin levels did not change over the period of study. However, the OSH cows had less myostatin in their plasma than the NZL and NZH cows, suggesting that there may be inhibition of muscle growth occurring in this strain.

The results of this study suggest that breakdown of muscle could be important in restoring the EB in high-producing dairy cows during peak lactation. Upregulation of the UbP pathway during the first four weeks of lactation may contribute to this muscle breakdown. However, it remains unclear what processes then continue to regulate breakdown of skeletal muscle to maintain the elevated abundance of troponin I-fs in plasma from four to 12 weeks postpartum in lactating dairy cows.

year: 2008

title: Collective writing: An inquiry into praxis

authors: Jandrić, Petar

subjects: collective writing

abstract: This is the second text in the series collectively written by members of the Editors' Collective, which comprises a series of individual and collaborative reflections upon the experience of contributing to the previous and first text written by the Editors' Collective: 'Towards a Philosophy of Academic Publishing.' In the article, contributors reflect upon their experience of collective writing and summarize the main themes and challenges. They show that the act of collective writing disturbs the existing systems of academic knowledge creation, and link these disturbances to the age of the digital reason. They conclude that the collaborative and collective action is a thing of learning-by-doing, and that collective writing seems to offer a possible way forward from the co-opting of academic activities by economics. Through detaching knowledge creation from economy, collaborative and collective writing address the problem of forming new collective intelligences.

text: Collective writing: An inquiry into praxis This is the second text in the series collectively written by members of the Editors' Collective, which comprises a series of individual and collaborative reflections upon the experience of contributing to the previous and first text written by the Editors' Collective: 'Towards a Philosophy of Academic Publishing.' In the article, contributors reflect upon their experience of collective writing and summarize the main themes and challenges. They show that the act of collective writing disturbs the existing systems of academic knowledge creation, and link these disturbances to the age of the digital reason. They conclude that the collaborative and collective action is a thing of learning-by-doing, and that collective writing seems to offer a possible way forward from the co-opting of academic activities by economics. Through detaching knowledge creation from economy, collaborative and collective writing address the problem of forming new collective intelligences.

year: 2017

title: Ko Tikanga Te Mātāmua:  ngā pūrākau, ngā pakiwaitara, me mihi, ka tika

authors: Carrucan, Edmond Thomas

subjects: Law

abstract: This study highlights pūrākau and pakiwaitara as legal precedents that can bring Tikanga to life in unique ways. Using Kaupapa Māori and Mana Tāne methodologies, I address two problems within a larger project towards further normalising Tikanga within the legal system and legal education.

The first problem is the key misconception that there are two primary sources of law: statutes and common law. My proposed solution involves reconceiving three primary sources of law: Tikanga, statutes and common law. The second problem is how to source from Tikanga in making legal arguments. My proposed solution encourages story analysis of pūrākau and pakiwaitara and the use of these legal precedents within legal submissions. Accordingly, this study has two purposes.

In embarking on my journey of storytelling, I address the first purpose which is to test whether Tikanga is the first law and supreme law of Aotearoa, as was the seminal proposition of Ani Mikaere. This addresses the key misconception referred to above, that there are only two primary sources of law. Through analysis of Tikanga jurists and Western jurists I conclude Mikaere was right. Tikanga is the supreme law of Aotearoa: Ko Tikanga Te Mātāmua. I propose a new model called Te Whānau Ture as a legal family of three primary law sources representing this finding.

This research then addresses the second purpose in showing how ngā pūrākau me ngā pakiwaitara make valuable contributions to the body of law: me mihi, ka tika. Here, this study proposes a new model called, Whai Matua o Te Ture Māori, a symbolic stingray comprised of fourteen objects of Māori law. Later, I propose a further model Ātea Whakaaro, to enable ethical legal story analysis.

This study responds to (a) indigenising legal education, (b) the inevitability of Tikanga test cases and (c) the current Ao Mārama model. The significance of pūrākau and pakiwaitara in legal settings emerges from this study and a reclaiming of a Māori Legal Method becomes inevitable.

text: Ko Tikanga Te Mātāmua:  ngā pūrākau, ngā pakiwaitara, me mihi, ka tika This study highlights pūrākau and pakiwaitara as legal precedents that can bring Tikanga to life in unique ways. Using Kaupapa Māori and Mana Tāne methodologies, I address two problems within a larger project towards further normalising Tikanga within the legal system and legal education.

The first problem is the key misconception that there are two primary sources of law: statutes and common law. My proposed solution involves reconceiving three primary sources of law: Tikanga, statutes and common law. The second problem is how to source from Tikanga in making legal arguments. My proposed solution encourages story analysis of pūrākau and pakiwaitara and the use of these legal precedents within legal submissions. Accordingly, this study has two purposes.

In embarking on my journey of storytelling, I address the first purpose which is to test whether Tikanga is the first law and supreme law of Aotearoa, as was the seminal proposition of Ani Mikaere. This addresses the key misconception referred to above, that there are only two primary sources of law. Through analysis of Tikanga jurists and Western jurists I conclude Mikaere was right. Tikanga is the supreme law of Aotearoa: Ko Tikanga Te Mātāmua. I propose a new model called Te Whānau Ture as a legal family of three primary law sources representing this finding.

This research then addresses the second purpose in showing how ngā pūrākau me ngā pakiwaitara make valuable contributions to the body of law: me mihi, ka tika. Here, this study proposes a new model called, Whai Matua o Te Ture Māori, a symbolic stingray comprised of fourteen objects of Māori law. Later, I propose a further model Ātea Whakaaro, to enable ethical legal story analysis.

This study responds to (a) indigenising legal education, (b) the inevitability of Tikanga test cases and (c) the current Ao Mārama model. The significance of pūrākau and pakiwaitara in legal settings emerges from this study and a reclaiming of a Māori Legal Method becomes inevitable.

year: 2021