• Adding value to milk by increasing its protein and CLA contents

      Murphy, J.J.; Stanton, Catherine; O'Donovan, Michael; Kavanagh, S.; Maher, J.; Patton, Joe; Mohammed, Riaz (Teagasc, 2008-08-01)
      The mid-summer milk protein study was undertaken on 34 commercial dairy farms in 2005 to evaluate the influence of dietary and management variables on milk protein content in mid-season. Data on grass composition, genetic merit of the herds and milk protein content were collected and analysed by multiple regression. Both calving date and genetic merit for milk protein content were significantly associated with milk protein content and were used as adjustment factors when evaluating the association between measures of grass quality and milk protein content. Milk protein content was associated with grass OMD (P = 0.04) and NDF content (P = 0.02) but not with CP content (P = 0.80). It is concluded that herds calving earlier, with a greater genetic merit for milk protein content and consuming better quality pasture would have greater milk protein contents in mid-season.
    • A comparison of energy balance and metabolic profiles of the New Zealand and North American strains of Holstein Friesian dairy cow

      Patton, Joe; Murphy, J.J.; O'Mara, Frank P.; Butler, Stephen T. (Cambridge University Press, 2008-06)
      The milk production, energy balance (EB), endocrine and metabolite profiles of 10 New Zealand Holstein Friesian (NZ) cows and 10 North American Holstein Friesian (NA) cows were compared. The NA cows had greater peak milk yields and total lactation milk yields (7387 v. 6208 kg; s.e.d.5359), lower milk fat and similar protein concentrations compared with the NZ cows. Body weight (BW) was greater for NA cows compared with NZ cows throughout lactation (596 v. 544 kg; s.e.d.515.5), while body condition score (BCS) tended to be lower. The NA strain tended to have greater dry matter intake (DMI) (17.2 v. 15.7 kg/day; s.e.d.50.78) for week 1 to 20 of lactation, though DMI as a proportion of metabolic BW was similar for both strains. No differences were observed between the strains in the timing and magnitude of the EB nadir, interval to neutral EB, or mean daily EB for week 1 to 20 of lactation. Plasma concentrations of glucose and insulin were greater for NA cows during the transition period (day 14 pre partum to day 28 post partum). Plasma IGF-I concentrations were similar for the strains at this time, but NZ cows had greater plasma IGF-I concentration from day 29 to day 100 of lactation, despite similar calculated EB. In conclusion, the results of this study do not support the premise that the NZ strain has a more favourable metabolic status during the transition period. The results, however, indicate that NZ cows begin to partition nutrients towards body reserves during mid-lactation, whereas NA cows continue to partition nutrients to milk production.
    • Differences in the expression of genes involved in the somatotropic axis in divergent strains of Holstein-Friesian dairy cows during early and mid lactation

      McCarthy, Sean D.; Butler, Stephen T.; Patton, Joe; Daly, Mairead; Morris, Dermot G.; Kenny, David A.; Waters, Sinead M. (Elsevier Inc. and American Dairy Science Association, 2009-10)
      Differences in genetic selection criteria for dairy cows internationally have led to divergence in the Holstein-Friesian breed. The objective of this study was to compare hepatic expression of genes of the somatotropic axis in the North American Holstein-Friesian and the New Zealand Holstein-Friesian strains of dairy cow at early and mid lactation. Mature cows of both the North American Holstein-Friesian (n = 10) and New Zealand Holstein-Friesian (n = 10) strains were selected. Liver tissue was collected by percutaneous punch biopsy from all cows at 35 and 140 d postpartum, representing early and mid lactation, respectively. Total RNA was extracted and the hepatic expression of genes involved in the control of the somatotropic axis was examined. Abundance of insulin-like growth factor (IGF)-1 mRNA was greater in the New Zealand strain, concomitant with a tendency for increased expression of acid-labile subunit mRNA. Across strains, mRNA abundance of IGF-binding protein-1, IGF-binding protein-2, and growth hormone receptor 1A decreased from d 35 to 140 postpartum, whereas expression of IGF-1 and acid-labile subunit tended to increase. Abundance of suppressor of cytokine signaling-3 mRNA was increased at d 140 postpartum. Both the strain of Holstein-Friesian cow and the stage of lactation influenced expression of genes controlling the somatotropic axis in hepatic tissue.
    • The effect of strain of Holstein-Friesian cow on size of ovarian structures, periovulatory circulating steroid concentrations, and embryo quality following superovulation

      de Feu, M.A.; Patton, Joe; Evans, A.C.O.; Lonergan, P.; Butler, Stephen T. (Elsevier Science Inc., 2008-10-15)
      When managed under grass-based systems of production, the NZ strain of Holstein-Friesian cow has superior reproductive performance compared to the NA strain despite having similar SCM yields. This study compared the ontogeny of early pregnancy events in NZ and NA cows. Ten NZ and 10 NA cows were submitted to a superovulation protocol on three occasions. Blood samples were collected daily from every cow from day -3 to +7 relative to a synchronised oestrus during each superovulation protocol. Pre-ovulatory oestradiol concentrations, follicle diameter, post-ovulatory progesterone concentrations, CL diameter, and circulating insulin-like growth factor-I concentrations did not differ between the two strains. Uteri were non-surgically flushed 7 d post AI, embryos were isolated and graded. The proportion of transferable embryos recovered was higher (P<0.01) in the NZ cows compared with the NA cows. A greater (P=0.01) proportion of the recovered structures were at the blastocyst stage in the NZ cows. Peak SCM yield and BCS at the time of peak SCM yield were not different between strains. However during the experimental period the NA cows maintained significantly higher daily SCM yields, whereas the NZ cows replenished significantly greater levels of BCS. The results indicate that differences in periovulatory steroid concentrations and size of ovarian structures do not explain the differences in embryo quality between the two strains. However, strain differences in nutrient partitioning from the time of peak SCM yield through late lactation may provide the key signals responsible for superior embryo quality in NZ cows.
    • Effects of negative energy balance on liver gene and protein expression during the early postpartum period and its impacts on dairy cow fertility

      Waters, Sinead M.; McCarthy, Sean D.; Morris, Dermot G.; Kenny, D.A.; Patton, Joe; Murphy, J.; Fenwick, M.; Wathes, D.C.; Fitzpatrick, Richard; Diskin, Michael G. (Teagasc, 2007-01-01)
      Negative energy balance (NEB) is a severe metabolic affecting high yielding dairy cows early post partum with both concurrent and latent negative effects on cow fertility as well as on milk production and cow health. The seasonal nature of Irish dairy production necessitates high cow fertility and a compact spring calving pattern in order to maximise grass utilisation. Poor dairy cow reproductive performance currently costs the Irish cattle industry in excess of €400 million annually. High milk yields have been associated with lower reproductive efficiency, and it has been suggested that this effect is probably mediated through its effects on the energy balance of the cow during lactation. The modern high genetic merit dairy cow prioritises nutrient supply towards milk production in early lactation and this demand takes precedence over the provision of optimal conditions for reproduction. In this study we used the bovine Affymetrix 23,000 gene microarray, which contains the most comprehensive set of bovine genes to be assembled and provides a means of investigating the modifying influences of energy balance on liver gene expression. Cows in severe negative energy balance (SNEB) in early lactation showed altered hepatic gene expression in metabolic processes as well as a down regulation of the insulin-like growth factor (IGF) system, where insulin like growth factor-1 (IGF-1), growth hormone receptor variant 1A (GHR1A) and insulin-like growth factor binding protein-acid labile subunit (IGFBP-ALS) were down regulated compared to the cows in the moderate negative energy balance MNEB group, consistent with a five-fold reduction in systemic concentrations of IGF1 in the SNEB group.Cows in SNEB showed elevated expression of key genes involved in the inflammatory response such as interleukin-8 (IL-8). There was a down regulation of genes involved in cellular growth in SNEB cows and moreover a negative regulator of cellular proliferation (HGFIN) was up regulated in SNEB cows, which is likely to compromise adaptation and recovery from NEB. The puma method of analysis revealed that 417 genes were differentially regulated by EB (P<0.05), of these genes 190 were up-regulated while 227 were down-regulated, with 405 genes having known biological functions. From Ingenuity Pathway Analysis (IPA), lipid catabolism was found to be the process most affected by differences in EB status.
    • Responses of North American and New Zealand strains of Holstein–Friesian dairy cattle to homeostatic challenges during early and mid-lactation

      Patton, Joe; Murphy, J.J.; O'Mara, Frank P.; Butler, Stephen T. (Cambridge University Press, 2009-02)
      This study investigated the physiological basis of differences in nutrient partitioning between the North American (NA) and New Zealand (NZ) strains of Holstein Friesian cattle by determining the responses to homeostatic challenges at two stages of lactation. Glucose tolerance tests, epinephrine challenges, and insulin challenges were carried out on consecutive days commencing on day 32 ± 0.48 (mean ± s.e.m) of lactation (T1) and again commencing on day 137 ± 2.44 of lactation (T2). The insulin and non-esterified fatty acid (NEFA) responses to glucose infusion did not differ between the strains. The NZ strain had a greater clearance rate (CR) of glucose (2.04 vs. 1.66 % / min) and tended to have a shorter (34.4 vs. 41.1 min) glucose half-life (t½) at T2 when infused with glucose. The NA cows had a greater glucose response to epinephrine infusion across T1 and T2, and tended to have a greater insulin response to epinephrine infusion. Plasma NEFA concentration declined to similar nadir concentrations for both strains at T1 in response to insulin, though from a higher basal concentration in NA cows, resulting in a greater (-2.29 vs. -1.38) NEFA area under the response curve (AUC) for NA cows. Glucose response to insulin varied with time, tending to be greater for NA at T1, but tending to be lower for NA at T2. The results indicated that NA cows had a greater glycogenolytic response to epinephrine, but both strains had similar lipolytic responses. The results also imply that higher basal circulating NEFA concentrations in the NA strain in early lactation were not due to diminished adipose tissue responsiveness to insulin. There were indications that glucose clearance rate was greater in NZ cows in mid-lactation, and may form the basis of increased body tissue accretion during mid- to late-lactation in this strain.