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Stahl L, Froels C, Sickinger M. Laparoskopische Ovariektomie bei einer Mutterkuh. Tierarztl Prax Ausg G Grosstiere Nutztiere 2022; 50:399-403. [DOI: 10.1055/a-1952-3216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
ZusammenfassungEine 13,25 Jahre alte Grauvieh-Mutterkuh wurde im Anschluss an eine Dystokie mit der Bitte um Kastration des Tieres an der Klinik für Wiederkäuer der Justus-Liebig-Universität Gießen vorgestellt. Die Kuh hatte bis zu diesem Zeitpunkt bereits 10 lebende Kälber geboren und wurde im Herdenverband mit Bulle auf der Weide gehalten. Da der Besitzer keine weitere Nutzung der Kuh zur Zucht beabsichtigte, dennoch aber der Wunsch zur weiteren Haltung des Tieres bestand, stellte er die Kuh an der Klinik vor. Die Vorstellung des Tieres erfolgte 6 Wochen nach der Kalbung mit Kalb bei Fuß. Das Kalb war von gutem Allgemeinbefinden, gutem Entwicklungs- und Ernährungszustand und wies keine klinischen Auffälligkeiten auf. Die Kuh zeigte sich sowohl in der allgemeinen als auch der speziellen gynäkologischen Untersuchung ohne besondere Befunde. Im Rahmen der transrektalen Untersuchung konnte der Uterus des Tieres unter der Hand versammelt werden und es lag keine Füllung des Organs vor. Der Uterus war schlaff und die Uteruswand wies keine Auffälligkeiten auf. Die Ovarien waren links 3×2x2 cm und rechts 3,5 × 2,5 × 2 cm groß. Es waren links keine Funktionsgebilde und rechts einzelne Follikel palpierbar. Die vaginoskopische Kontrolle ergab keine von der Norm abweichenden Befunde. Aufgrund der physiologischen Puerperalsituation wurde die Kastration der Kuh als laparoskopische Ovariektomie von der linken Flanke aus am stehenden Tier durchgeführt. Die Kuh wies in den Tagen nach der Operation ein ungestörtes Allgemeinbefinden sowie keinerlei Schmerzhaftigkeit bei der transrektalen Palpation der Amputationsstümpfe auf und konnte 2 Tage nach endoskopischer Kastration in den Heimatbestand entlassen werden. Anhand des hier vorgestellten Falles soll zum einen die Technik der Endoskopie-gestützten Ovariektomie demonstriert werden. Andererseits soll gezeigt werden, dass die Kastration von Kühen ein probates Mittel darstellt, Kühe, die nicht mehr für die Zucht genutzt werden sollen, weiterhin im Herdenverband halten zu können. Dies erscheint insbesondere für Mutterkuhhalter und Hobbyhalter von zunehmendem Interesse zu sein.
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Affiliation(s)
- Lydia Stahl
- Klinik für Wiederkäuer, Klinikum Veterinärmedizin, Justus-Liebig-Universität Gießen
| | - Coco Froels
- Klinik für Geburtshilfe, Gynäkologie und Andrologie der Groß- und Kleintiere, Klinikum Veterinärmedizin, Justus-Liebig-Universität Gießen
| | - Marlene Sickinger
- Klinik für Wiederkäuer, Klinikum Veterinärmedizin, Justus-Liebig-Universität Gießen
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Abstract
An understanding of the anatomy, histology, and development of the equine mammary gland underpins study of the pathology of diseases including galactorrhoea, agalactia, mastitis, and mammary tumour development. This review examines the prenatal development of the equine mammary gland and the striking degree to which the tissue undergoes postnatal development associated with the reproductive cycle. The gland is characterised by epithelial structures arranged in terminal duct lobular units, similar to those of the human breast, supported by distinct zones of intra- and interlobular collagenous stroma. Mastitis and mammary carcinomas are two of the most frequently described equine mammary pathologies and have an overlap in associated clinical signs. Mastitis is most frequently associated with bacterial aetiologies, particularly Streptococcus spp., and knowledge of the process of post-lactational regression can be applied to preventative husbandry strategies. Equine mammary tumours are rare and carry a poor prognosis in many cases. Recent studies have used mammosphere assays to reveal novel insights into the identification and potential behaviour of mammary stem/progenitor cell populations. These suggest that mammospheres derived from equine cells have different growth dynamics compared to those from other species. In parallel with studying the equine mammary gland in order to advance knowledge of equine mammary disease at the interface of basic and clinical science, there is a need to better understand equine lactational biology. This is driven in part by the recognition of the potential value of horse and donkey milk for human consumption, particularly donkey milk in children with 'Cow Milk Protein Allergy'.
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Affiliation(s)
- Katherine Hughes
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
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Hughes K. Comparative mammary gland postnatal development and tumourigenesis in the sheep, cow, cat and rabbit: Exploring the menagerie. Semin Cell Dev Biol 2020; 114:186-195. [PMID: 33082118 DOI: 10.1016/j.semcdb.2020.09.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 09/11/2020] [Accepted: 09/21/2020] [Indexed: 02/06/2023]
Abstract
Sheep, cows, cats, and rabbits are kept by humans for agricultural purposes and as companion animals. Much of the mammary research in these species has focussed on mastitis in the case of ruminants and rabbits, and mammary tumourigenesis in cats and rabbits. However, similarities with the human breast suggest that these species may be currently underutilised as valuable comparative models of breast development and disease. The mammary gland undergoes cyclical postnatal development that will be considered here in the context of these non-traditional model species, with a focus on the mammary microenvironment at different postnatal developmental stages. The second part of this review will consider mammary tumour development. Ruminants are thought to be relatively 'resistant' to mammary tumourigenesis, likely due to multiple factors including functional properties of ruminant mammary stem/progenitor cells, diet, and/or the fact that production animals undergo a first parity soon after puberty. By contrast, unneutered female cats and rabbits have a propensity to develop mammary neoplasms, and subsets of these may constitute valuable comparative models of breast cancer.
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Affiliation(s)
- Katherine Hughes
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom.
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Ortega S, Halicek M, Fabelo H, Callico GM, Fei B. Hyperspectral and multispectral imaging in digital and computational pathology: a systematic review [Invited]. BIOMEDICAL OPTICS EXPRESS 2020; 11:3195-3233. [PMID: 32637250 PMCID: PMC7315999 DOI: 10.1364/boe.386338] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 03/28/2020] [Accepted: 05/08/2020] [Indexed: 05/06/2023]
Abstract
Hyperspectral imaging (HSI) and multispectral imaging (MSI) technologies have the potential to transform the fields of digital and computational pathology. Traditional digitized histopathological slides are imaged with RGB imaging. Utilizing HSI/MSI, spectral information across wavelengths within and beyond the visual range can complement spatial information for the creation of computer-aided diagnostic tools for both stained and unstained histological specimens. In this systematic review, we summarize the methods and uses of HSI/MSI for staining and color correction, immunohistochemistry, autofluorescence, and histopathological diagnostic research. Studies include hematology, breast cancer, head and neck cancer, skin cancer, and diseases of central nervous, gastrointestinal, and genitourinary systems. The use of HSI/MSI suggest an improvement in the detection of diseases and clinical practice compared with traditional RGB analysis, and brings new opportunities in histological analysis of samples, such as digital staining or alleviating the inter-laboratory variability of digitized samples. Nevertheless, the number of studies in this field is currently limited, and more research is needed to confirm the advantages of this technology compared to conventional imagery.
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Affiliation(s)
- Samuel Ortega
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA
- Institute for Applied Microelectronics (IUMA), University of Las Palmas de Gran Canaria (ULPGC), Campus de Tafira, 35017, Las Palmas de Gran Canaria, Las Palmas, Spain
- These authors contributed equally to this work
| | - Martin Halicek
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA
- Department of Biomedical Engineering, Georgia Inst. of Tech. and Emory University, Atlanta, GA 30322, USA
- These authors contributed equally to this work
| | - Himar Fabelo
- Institute for Applied Microelectronics (IUMA), University of Las Palmas de Gran Canaria (ULPGC), Campus de Tafira, 35017, Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Gustavo M Callico
- Institute for Applied Microelectronics (IUMA), University of Las Palmas de Gran Canaria (ULPGC), Campus de Tafira, 35017, Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Baowei Fei
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA
- University of Texas Southwestern Medical Center, Advanced Imaging Research Center, Dallas, TX 75235, USA
- University of Texas Southwestern Medical Center, Department of Radiology, Dallas, TX 75235, USA
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Zhou Z, Bian C, Luo Z, Guille C, Ogunrinde E, Wu J, Zhao M, Fitting S, Kamen DL, Oates JC, Gilkeson G, Jiang W. Progesterone decreases gut permeability through upregulating occludin expression in primary human gut tissues and Caco-2 cells. Sci Rep 2019; 9:8367. [PMID: 31182728 PMCID: PMC6558054 DOI: 10.1038/s41598-019-44448-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 05/14/2019] [Indexed: 02/06/2023] Open
Abstract
Progesterone plays a protective role in preventing inflammation and preterm delivery during pregnancy. However, the mechanism involved is unknown. Microbial product translocation from a permeable mucosa is demonstrated as a driver of inflammation. To study the mechanism of the protective role of progesterone during pregnancy, we investigated the effect of physiologic concentrations of progesterone on tight junction protein occludin expression and human gut permeability in vitro and systemic microbial translocation in pregnant women in vivo. Plasma bacterial lipopolysaccharide (LPS), a representative marker of in vivo systemic microbial translocation was measured. We found that plasma LPS levels were significantly decreased during 24 to 28 weeks of gestation compared to 8 to 12 weeks of gestation. Moreover, plasma LPS levels were negatively correlated with plasma progesterone levels but positively correlated with plasma tumor necrosis factor-alpha (TNF-α) levels at 8 to 12 weeks of gestation but not at 24 to 28 weeks of gestation. Progesterone treatment increased intestinal trans-epithelial electrical resistance (TEER) in primary human colon tissues and Caco-2 cells in vitro through upregulating tight junction protein occludin expression. Furthermore, progesterone exhibited an inhibitory effect on nuclear factor kappa B (NF-κB) activation following LPS stimulation in Caco-2 cells. These results reveal a novel mechanism that progesterone may play an important role in decreasing mucosal permeability, systemic microbial translocation, and inflammation during pregnancy.
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Affiliation(s)
- Zejun Zhou
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, 410081, China
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Chuanxiu Bian
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, 29425, USA
- School of Medicine, Jiangsu University, Zhenjiang, Jiangsu, 212013, China
| | - Zhenwu Luo
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Constance Guille
- Department of Psychiatry and Behavioral Sciences, College of Medicine, Medical University of South Carolina, Charleston, SC, 29425, USA
- Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Elizabeth Ogunrinde
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Jiapeng Wu
- Biochemistry, Biophysics and Molecular Biology, Whitman College, Walla Walla, WA, 99362, USA
| | - Min Zhao
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, 29425, USA
- Department of Biochemistry, Basic Medical College, Hubei University of Chinese Medicine, Wuhan, 430065, China
| | - Sylvia Fitting
- Department of Psychology & Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Diane L Kamen
- Medical Research Service, Ralph H. Johnson VAMC, Medical University of South Carolina, Charleston, SC, 29403, USA
| | - Jim C Oates
- Medical Research Service, Ralph H. Johnson VAMC, Medical University of South Carolina, Charleston, SC, 29403, USA
- Division of Rheumatology, Department of Medicine, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Gary Gilkeson
- Medical Research Service, Ralph H. Johnson VAMC, Medical University of South Carolina, Charleston, SC, 29403, USA.
- Division of Rheumatology, Department of Medicine, Medical University of South Carolina, Charleston, SC, 29425, USA.
| | - Wei Jiang
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, 29425, USA.
- Division of Infectious Diseases, Department of Medicine, Medical University of South Carolina, Charleston, SC, 29425, USA.
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Review: The pre-pubertal bovine mammary gland: unlocking the potential of the future herd. Animal 2019; 13:s4-s10. [DOI: 10.1017/s1751731119001204] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Akers RM. TRIENNIAL LACTATION SYMPOSIUM/BOLFA: Plasticity of mammary development in the prepubertal bovine mammary gland. J Anim Sci 2018; 95:5653-5663. [PMID: 29293751 DOI: 10.2527/jas2017.1792] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Although peripubertal mammary development represents only a small fraction of the total mass of mammary parenchyma present in the udder at the end of gestation and into lactation, there is increasing evidence that the tissue foundations created in early life can affect future mammary development and function. Studies on expression of estrogen and progesterone receptors seem to confirm the relevance of these steroids in prepubertal mammary development, but connections with other growth factors, hormones, and local tissue factors remain elusive. Enhanced preweaning feeding in the bovine appears to enhance the capacity of mammary tissue to response to mammogenic stimulation. This suggests the possibility that improved early nutrition might allow for creation of stem or progenitor cell populations to better support the massive ductal growth and lobulo-alveolar development during gestation. Increasing evidence that immune cells are involved in mammary development suggests there are unexpected and poorly understood connections between the immune system and mammary development. This is nearly unexplored in ruminants. Development of new tools to identify, isolate, and characterize cell populations within the developing bovine mammary gland offer the possibility of identifying and perhaps altering populations of mammary stem cells or selected progenitor cells to modulate mammary development and, possibly, mammary function.
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Akers RM. A 100-Year Review: Mammary development and lactation. J Dairy Sci 2017; 100:10332-10352. [DOI: 10.3168/jds.2017-12983] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 06/15/2017] [Indexed: 01/13/2023]
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Geiger A, Parsons C, Akers R. Feeding an enhanced diet to Holstein heifers during the preweaning period alters steroid receptor expression and increases cellular proliferation. J Dairy Sci 2017; 100:8534-8543. [DOI: 10.3168/jds.2017-12791] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 06/07/2017] [Indexed: 11/19/2022]
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Magro G, Brevini TAL, De Maglie M, Minozzi G, Scanziani E, Piccinini R. An explant of heifer mammary gland to study the immune response of the organ. Res Vet Sci 2017; 114:44-50. [PMID: 28314156 DOI: 10.1016/j.rvsc.2017.03.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 02/27/2017] [Accepted: 03/04/2017] [Indexed: 11/19/2022]
Abstract
Continuous or primary epithelial cell lines have been extensively used to study the mammary gland immune response, but they are constituted by a single cell population. Our aim was to test whether an explant of heifer gland, where the tissue structure is maintained, might be a valid model to investigate the innate immune response to infection. The study was carried out on 2mm3-sections of heifer udders, in 2 consecutive trials, using LPS or LTA in the first trial and two different concentrations of Staphylococcus aureus (Staph. aureus) in the second. Treated and untreated sections were collected after 1h, 3h and 6h incubation; in the first trial, a final time-point at 18h was considered. The mRNA expression of TNFα, IL-1β, IL-6, IL-8 and LAP was analyzed by quantitative real-time PCR. Histological examination showed well-preserved morphology of the tissue, and apoptosis only showed a slight, not significant increase throughout the experiment. IL-1β and IL-6 were significantly up-regulated, in response to LPS or Staph. aureus, while TNF-α and IL-8 significantly increased only under LPS treatment. LAP expression showed a significant late increase when stimulated by LPS. The immunochemical staining of the sections demonstrated a higher number of T lymphocytes within the alveolar epithelium, in comparison with interstitial localization. Since the explants belonged to pubertal non-pregnant heifers, T cells may be regarded as resident cells, suggesting their participation in the regulation of mammary homeostasis. Therefore, applying our model would give new insights in the investigation of udder pathophysiology.
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Affiliation(s)
- Giada Magro
- Department of Veterinary Medicine, University of Milan, via Celoria 10, 20133 Milano, Italy
| | - Tiziana A L Brevini
- Department of Health, Animal Science and Food Safety, University of Milan, via Celoria 10, 20133 Milano, Italy
| | - Marcella De Maglie
- Department of Veterinary Medicine, University of Milan, via Celoria 10, 20133 Milano, Italy
| | - Giulietta Minozzi
- Department of Veterinary Medicine, University of Milan, via Celoria 10, 20133 Milano, Italy
| | - Eugenio Scanziani
- Department of Veterinary Medicine, University of Milan, via Celoria 10, 20133 Milano, Italy
| | - Renata Piccinini
- Department of Veterinary Medicine, University of Milan, via Celoria 10, 20133 Milano, Italy.
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Tucker H, Beaudry K, Parsons C, Ellis S, Akers R. Impaired mammary development in tamoxifen-treated prepubertal heifers is associated with altered development and morphology of myoepithelial cells. J Dairy Sci 2016; 99:10093-10101. [DOI: 10.3168/jds.2016-11550] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/18/2016] [Indexed: 01/15/2023]
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12
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Geiger A, Parsons C, Akers R. Feeding a higher plane of nutrition and providing exogenous estrogen increases mammary gland development in Holstein heifer calves. J Dairy Sci 2016; 99:7642-7653. [DOI: 10.3168/jds.2016-11283] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 05/27/2016] [Indexed: 12/12/2022]
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Al Naib A, Tucker H, Xie G, Keisler D, Bartol F, Rhoads R, Akers R, Rhoads M. Prepubertal tamoxifen treatment affects development of heifer reproductive tissues and related signaling pathways. J Dairy Sci 2016; 99:5780-5792. [DOI: 10.3168/jds.2015-10679] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 03/02/2016] [Indexed: 11/19/2022]
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Tucker HLM, Parsons CLM, Ellis S, Rhoads ML, Akers RM. Tamoxifen impairs prepubertal mammary development and alters expression of estrogen receptor α (ESR1) and progesterone receptors (PGR). Domest Anim Endocrinol 2016; 54:95-105. [PMID: 26619291 DOI: 10.1016/j.domaniend.2015.10.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/13/2015] [Accepted: 10/13/2015] [Indexed: 11/23/2022]
Abstract
Research has shown that prepubertal heifers experience allometric mammary growth that is influenced by the ovaries. Our purpose was to determine the role of estrogen in prepubertal mammary gland development. Sixteen Holstein calves were randomly assigned to 1 of 2 treatment groups: tamoxifen-injected (TAM) or control (CON). Calves were administered the antiestrogen tamoxifen (0.3 mg kg(1) d(1)) or placebo from 28 to 120 d of age. At 120 d, calves were euthanized and udders removed. Weight and DNA content of trimmed parenchymal tissue were halved (P ≤ 0.0001) in TAM compared with CON calves. Parenchymal samples from 3 zones of the left rear mammary gland (lower, middle, and outer regions) were processed for immunohistochemical staining for estrogen receptor α (ESR1) and progesterone receptor (PGR), Ki67-positive cells, and 5-bromo-2'-deoxyuridine label retaining cells (LRCs). Overall, neither the percentage nor location within the epithelial tissue layer of either ESR1- or PGR-positive cells was impacted by TAM treatment. However, image analysis indicated a 6.2-fold lower (P = 0.0001) level of ESR1 protein expression in TAM calves. Similarly, messenger RNA expression of ESR1 was also reduced (P = 0.0001) in TAM heifers. In contrast, expression of PGR protein was greater by 43% (P = 0.03) in TAM calves, but messenger RNA expression did not differ between treatments. Overall, TAM calves had a higher (P ≤ 0.03) percentage and density (cells per tissue area) of Ki67-positive cells. Irrespective of treatment, there were also more Ki67-labeled cells in the outer zones of the mammary gland (P ≤ 0.001). We were able to effectively use multispectral imaging to identify positive cells and quantify the expression of ESR1 and PGR protein. We also identified and counted the proportion of label retaining cells (LCR) (putative epithelial stem cells). We noted an overall 2.9-fold greater number of LRCs in TAM heifers and more LRCs in the outer sampling zones. This suggests that a cohort of LCR cells in TAM remained inactivated in comparison with CON heifers, which exhibited markedly increased growth of the mammary parenchymal tissue over the treatment period. These results suggest that the impacts of ovariectomy are partially explained by loss of ESR1 expression and/or estrogen receptor signaling in the prepubertal bovine mammary gland. The significance of mammary expression of PGR in control of prepubertal bovine mammary development remains unresolved.
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Affiliation(s)
- H L M Tucker
- Department of Dairy Science, Virginia Tech, Blacksburg, VA, 24061, USA
| | - C L M Parsons
- Department of Dairy Science, Virginia Tech, Blacksburg, VA, 24061, USA
| | - S Ellis
- Biological Sciences Directorate, National Science Foundation, Arlington, VA 22230, USA
| | - M L Rhoads
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA, 24061, USA
| | - R M Akers
- Department of Dairy Science, Virginia Tech, Blacksburg, VA, 24061, USA.
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