Behavioural and physiological responses of heifer calves to acute stressors: long-term consistency and relationship with adult reactivity to milking

The present study investigated the long-term consistency of individual differences in dairy cattles’ responses in tests of behavioural and hypothalamo–pituitary–adrenocortical (HPA) axis reactivity, as well as the relationship between responsiveness in behavioural tests and the reaction to first milking. Two cohorts of heifer calves, Cohorts 1 (N = 25) and 2 (N = 16), respectively, were examined longitudinally from the rearing period until adulthood. Cohort 1 heifers were subjected to open field (OF), novel object (NO), restraint, and response to a human tests at 7 months of age, and were again observed in an OF test during first pregnancy between 22 and 24 months of age. Subsequently, inhibition of milk ejection and stepping and kicking behaviours were recorded in Cohort 1 heifers during their first machine milking. Cohort 2 heifers were individually subjected to OF and NO tests as well as two HPA axis reactivity tests (determining ACTH and/or cortisol response profiles after administration of exogenous CRH and ACTH, respectively) at 6 months of age and during first lactation at approximately 29 months of age. Principal component analysis (PCA) was used to condense correlated response measures (to behavioural tests and to milking) within ages into independent dimensions underlying heifers’ reactivity. Heifers demonstrated consistent individual differences in locomotion and vocalisation during an OF test from rearing to first pregnancy (Cohort 1) or first lactation (Cohort 2). Individual differences in struggling in a restraint test at 7 months of age reliably predicted those in OF locomotion during first pregnancy in Cohort 1 heifers. Cohort 2 animals with high cortisol responses to OF and NO tests and high avoidance of the novel object at 6 months of age also exhibited enhanced cortisol responses to OF and NO tests at 29 months of age. Measures of HPA axis reactivity, locomotion, vocalisation and adrenocortical and behavioural responses to novelty were largely uncorrelated, supporting the idea that stress responsiveness in dairy cows is mediated by multiple independent underlying traits. Inhibition of milk ejection and stepping and kicking behaviours during first machine milking were not related to earlier struggling during restraint, locomotor responses to OF and NO tests, or the behavioural interaction with a novel object. Heifers with high rates of OF and NO vocalisation and short latencies to first contact with the human at 7 months of age exhibited better milk ejection during first machine milking. This suggests that low underlying sociality might be implicated in the inhibition of milk ejection at the beginning of lactation in heifers.

An algorithm to predict pregnancy in assisted conception

BACKGROUND: Male fertility potential cannot be measured by conventional parameters for assisted reproduction by intracytoplasmic sperm injection. This study determines the relationship between testicular and ejaculated sperm mitochondrial (mt) DNA deletions, nuclear (n) DNA fragmentation and fertilisation and pregnancy rates in ICSI. METHODS: Ejaculated sperm were obtained from 77 men and testicular sperm from 28 men with obstructive azoospermia undergoing ICSI. Testicular sperm were retrieved using a Trucut needle. MtDNA analysed using a long polymerase chain reaction. The alkaline Comet assay determined nDNA fragmentation. RESULTS: Of subjects who achieved a pregnancy (50%) using testicular sperm, only 26% had partners�??�?�¢?? sperm with wild type (WT) mtDNA. Of pregnant subjects (38%) using ejaculated sperm, only 8% had partner sperm with WT mtDNA.. In each, the successful group had less mtDNA deletions and less nDNA fragmentation. There were inverse relationships between pregnancy and mtDNA deletion numbers, size and nDNA fragmentation for both testicular and ejaculated sperm. No relationships were observed with fertilisation rates. An algorithm for the prediction of pregnancy is presented based on the quality of sperm nDNA and mtDNA. CONCLUSION: In both testicular and ejaculated sperm, mtDNA deletions and nDNA fragmentation are closely associated with pregnancy in ICSI.

Homocysteine is lower in the Third Trimester of Pregnancy in Women with Enhanced Folate status from continued Folic Acid Supplementation.

Background: In many countries current recommendations are that women take a daily 400ug folic acid supplement, from before conception until the end of the 12th week of gestation, for the prevention of neural tube defects. Low folate status is associated with an elevated concentration of plasma total homocysteine (tHcy), a risk factor that is associated with pregnancy complications such as pre-eclampsia. Methods: In a longitudinal study, tHcy and corresponding folate status were determined in 101 pregnant women at 12, 20 and 35 weeks of gestation, in 35 non-pregnant control subjects sampled conconcurrently, and in a subgroup (n=21 pregnant, 19 non-pregnant women) at 3 days post-partum. Results: Plasma tHcy concentrations were significantly lower throughout pregnancy compared with control subjects, with values lowest in the 2nd trimester before increasing toward non-pregnant values in the 3rd trimester. Importantly, tHcy concentrations were lower in pregnant women taking folic acid supplements compared to those not, an effect which reached significance in the 3rd trimester (5.25 umol/l v 6.89 umol/l, P <0.05). Furthermore, during the 3rd trimester, tHcy concentrations were significantly higher in pregnant women with a history of miscarriage compared to those with no previous history (7.32 umol/l v 5.62 u­mol/l, P <0.01). Conclusion: This is the first longitudinal study to show that homocysteine levels rise in late pregnancy towards non-pregnant levels; a rise which can be limited by enhancing folate status through continued folic acid supplementation. These results indicate a potential role for continued folic acid supplementation in reducing pregnancy complications associated with hyperhomocysteinaemia.