Molecular and cellular effects of gestational diet on the developing bovine reproductive and immune systems

Ruiz-Diaz, Maria Dolores (2019) Molecular and cellular effects of gestational diet on the developing bovine reproductive and immune systems. PhD thesis, University of Nottingham.

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Protein deficient diets are common in the range beef production system employed in northern Australia. This reflects variation in pasture quality due to local climatic conditions, notably the annual rainy and dry seasons. It is well documented that changes in maternal nutrition during pregnancy can affect the fetal developmental program. The reproductive and immune systems have been demonstrated to be influenced by maternal nutrition; however, much remains unknown. Therefore, the aims of this project were to study the impact of maternal dietary protein intake, mimicking the rainy (14% crude protein dietary content) and the dry (7% crude protein) Australian seasons on the development of the (i) reproductive tract and (ii) immune system of 98 day old bovine fetuses, and on the development of 20 month old bulls. To this end, cows were fed isocalorific high (14%) and low (7%) protein diets during the peri - conception period (60 days prior artificial insemination to 23 days post - conception (dpc)) and then the groups were split into two further groups, half of which remained with the same peri – conception diet, whereas the other half was switched to the opposite diet until 98 dpc (end of the first trimester). This two factorial experimental design provided us with four different dietary groups (low-low, LL; low-high, LH; high-low, HL; and high-high, HH, where low is defined as 7% protein and high as 14% protein), as well as with two different diets per period (LPeri, HPeri, LPost and HPost). The tissues analysed to assess the reproductive tract were the testes in 98 dpc fetuses and the testes and the epididymis in the 20 month old animals. Data pertaining to the fetal testicular cells number, seminiferous tubule abundance and size and blood vessel quantity and size from fetal and adult testis and adult epididymis were collected using a range of histological techniques and statistical analyses. In addition, proteomic analysis of the epididymal fluid extracted from the 20 month old bulls was performed.

Testicular cell proportions within the d98 testis were affected by the different diets; thus in 98 dpc LL fetuses a decrease in the percentage of Leydig cell and an increase in the percentage of germ cells and in the number of seminiferous tubules compared with the other diet regimes was observed. In addition, the proportion of seminiferous tubules was reduced in the 98 dpc fetuses from the HL group compared to the other diet regimes and tubule size was smaller in 98 dpc LPost fetuses compared with HPost. No significant differences were found in the number, percentage and size of seminiferous tubules, epididymal tubule and blood vessels in 20 month old bulls testis or epididymis, except for a decrease in the percentage of the seminiferous tubules in the adult testes in LPeri compared with HPeri and the number of testicular blood vessels in the LPost compared with the HPost. However, the protein profile of the epididymis fluid from adult bulls showed alterations in proteins that are involved in male fertility related with low protein diets, affecting maturation, capacitation, motility and sperm – zona pellucida binding.

Regarding the assessment of the immune system, thymus and thyroid tissues were collected from 98 dpc male and female fetuses and prescapular lymph node and surrounded adipose tissues were retrieved from the 20 month old bulls. Thymus gene expression was determined using RNA sequencing and qPCR analysis. Changes in genes potentially involved in thymus development and function were observed between diets and/or sexes. In addition, fatty acids were extracted from the pre-scapular lymph node (LN), perinodal adipose tissue (PAT) and further adipose tissue (WAT) surrounding the pre - scapular lymph node. Fatty acid profiles showed significant differences in the percentage of C14:0, C14:1, C18:0 and C18:1n9c present in LN and the percentage of C16:0 present in WAT during the peri - conception period. A decrease in C18:0 was also observed in LL compared with HL and HH groups in the LN and an increase in C16:0 in LH compared to HL and HH groups in WAT. In conclusion, manipulation of maternal protein intake during early stages of pregnancy altered the reproductive and the immune system tissues development. Whereas histological changes were compensated for later in life, molecular changes were observed in adulthood.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Rutland, Catrin
Mongan, Nigel
Perry, Viv
Keywords: Testis, Thymus, Early development, Maternal nutrition
Subjects: S Agriculture > SF Animal culture
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Veterinary Medicine and Science
Item ID: 55661
Depositing User: Ruiz-Diaz, Maria
Date Deposited: 15 Apr 2019 12:16
Last Modified: 07 May 2020 13:31

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