@conference {69469,
	title = {Asssociation among hormones and metabolites during the transition period and early lactation milk production},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {70},
	year = {2010},
	month = {Jun},
	pages = {51-56},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {The transition period is loosely defined as the period from three weeks pre-calving to three weeks post calving, and is regarded as a very important determinant of a cow{\textquoteright}s lactation performance. Data were collated from three experiments in which blood was sampled repeatedly pre- and post-calving and milk production was recorded post-calving. Data were pooled within treatment and associations between blood hormones and metabolites, and milk production determined using regression analysis. Milk and milk solids (MS) yield were positively associated (P <0.05) with pre-calving plasma leptin and glucose concentrations and milk yield was negatively associated (P <0.05) with pre-calving non-esterified fatty acid (NEFA) and β-hydroxy butyrate concentrations. Milk yield was negatively associated (P <0.05) with plasma growth hormone, aspartate aminotransferase, and glutamate dehydrogenase concentrations in the first days of lactation, and with insulin like growth factor and glucose concentrations during the first five weeks post-calving. In comparison, plasma NEFA and albumin (ALB) concentrations post-calving and the ratio of NEFA to ALB were all positively associated (P <0.05) with milk and MS yield during the first five weeks of lactation. Data are consistent with a positive effect of calving body condition on milk production and an increased milk production with increasing condition score loss post-calving.},
	issn = {1176-5283},
	author = {Edwards P and Mandok K and Lee JM and Burke CR and Kolver ES and Roche JR}
}
@conference {41670,
	title = {Diet or strain: Effects on postpartum anovulatory interval in dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {339-343},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {Changes in cow genetics and systems of farming have had large effects on the reproductive performance of dairy cows. The objective of this study was to determine if grain supplementation modified the previously identified effects of Holstein-Friesian (HF) strain on the postpartum anoestrus interval (PPAI). Thirty multiparous Overseas (OS) HF and 30 New Zealand-HF cows from a 1990s strain (NZ) were offered unrestricted access to fresh pasture and randomly allocated to three levels of a maize and barley-based concentrate supplementation (0, 3 or 6 kg DM/day). Postpartum anovulatory interval (PPAI) was not significantly affected by either strain or diet, and there was no significant strain x diet interaction. Results suggest that the nutritional requirements necessary for multiparous NZ or OS HF cows to resume oestrous cycles before 40 days postpartum can be achieved when offered unrestricted access to high quality pasture. In this circumstance, additional concentrate feeding did not alter the length of the postpartum anoestrous interval. },
	issn = {1176-5283},
	author = {Chagas LM and Gore PJS and Sheahan AJ and Lee JM and Watkins KA and Aspin PW and Roche JR}
}
@conference {41921,
	title = {A nutrient-signalling effect of grain feeding on postpartum anovulatory intervals in mature dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {334-338},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {Our previous study with mature dairy cows found that increased pasture intakes in early lactation resulted in more milk being produced but with no change in postpartum anovulatory intervals (PPAI). The present study used a 2 x 2 factorial to determine PPAI in 68 cows with pre- and post-calving diets that were iso-energetic, but varying in the ratio of structural to non-structural carbohydrate. At 36 {\textpm} 8.7 days prepartum, cows were assigned iso-energetic diets (114 MJ ME/cow/day) of either pasture/pasture silage (n=34) or the same diet supplemented with 3 kg DM/cow/d barley-maize concentrate (n=34). After calving, cows within each prepartum diet were assigned iso-energetic diets (179 MJ ME/cow/d) of either pasture/pasture silage (n=34) or the same diet supplemented with 5 kg DM/cow/d concentrate (n=34). Postpartum grain feeding reduced (P < 0.05) PPAI (28.4 {\textpm} 1.8 day) compared to the pasture/pasture silage only diet (36.4 {\textpm} 2.5 day). Prepartum diet did not affect PPAI. Body condition score was inversely related to PPAI at all time points (P < 0.05), but explained little (5-12\%) of the variability in PPAI. Significant relationships to PPAI were also found for blood non-esterified fatty acids, urea and magnesium, but again, r2-values were <= 0.1. None of the milk characteristics measured were significantly related to PPAI. This study supports the premise that discrete or specific nutritional cues unrelated to general energy status can favourably target physiological functions in reproductive tissues at the brain and/or ovarian levels. },
	issn = {1176-5283},
	author = {Burke CR and Roche JR and Aspin PW and Lee JM}
}
@conference {41937,
	title = {Supplementation with concentrates either pre- or post-partum does not affect milk production when diets are iso-energetic},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {416-422},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {Dairy cow glucose requirements increase dramatically during the weeks preceding calving, suggesting that supplements that increase glucose supply (rapidly fermentable carbohydrates) would reduce precalving mobilisation of body tissue and improve subsequent milk production. Sixty-eight multiparous dairy cows were randomly allocated to one of two diets for 36 {\textpm} 8.7 days precalving. All cows were fed pasture and pasture-silage precalving, with one group also receiving 3kg DM of a barley-maize concentrate. Precalving diets were iso-energetic (114 MJ/cow/day). At calving, cows within each precalving feeding treatments were randomly allocated to two dietary treatments for 35 days in a 2x2 factorial arrangement. Postcalving, all cows received pasture and pasture silage with one group also receiving 5.0 kg DM of a barley-maize concentrate. Postcalving diets were also iso-energetic (179 MJ/cow/day). Milk yield and composition, and liveweight (LW) and body condition score (BCS) were assessed weekly for five weeks. Blood was sampled on day -21, -14, -7, 0, 1, 2, 3, 4, 7, 14, 21, 28 and 35 relative to calving, and plasma samples were analysed for indicators of energy status. Average milksolids yield (1.9 kg/cow/d) during the five weeks postcalving was not affected by either pre- or postcalving concentrate supplementation, although protein to fat ratio was higher in supplemented cows. Similarly, concentrate supplementation pre- or postcalving did not affect either LW or BCS change before or after calving. Cows receiving concentrates precalving had higher (P<0.001) plasma non-esterified fatty acid (NEFA) concentrations, but otherwise were not different to those receiving an equivalent energy intake from pasture and pasture silage. Postcalving concentrate supplementation increased (P<0.01) plasma glucose and NEFA and decreased (P<0.001) plasma B-OH butyrate. Results suggests little effect on milk production by replacing energy from structural carbohydrates in high quality pasture with energy from non-structural carbohydrate during the transition period. },
	issn = {1176-5283},
	author = {Roche JR and Lee JM and Aspin PW and Sheahan AJ and Burke CR and Kolver ES and Sugar B and Napper AR}
}
@conference {41571,
	title = {Effect of pre- and postpartum pasture feeding intakes on postpartum anoestrous intervals in dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {221-224},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Extended postpartum anoestrous intervals (PPAI) are the predominant source of infertility on New Zealand dairy farms. A 2 x 2 factorial design was used to investigate pre- and postpartum pasture feeding levels on PPAI. Sixty-eight multiparous Holstein-Friesian dairy cows due to calve in the first three weeks of the calving period were randomly assigned to a high (11.9 kg DM/cow/day) or low (4.8 kg DM/cow/day) pasture feeding intake for 29 {\textpm} 7.7 days pre partum. After calving, cows within each prepartum feeding level were assigned to a high (13.5 kg DM/cow/day) or low (8.6 kg DM/cow/day) pasture feeding intake for 35 days. At 35 days post partum, cows were grazed as a single group with pasture silage supplementation. Concentrations of progesterone were determined in milk samples collected on Mondays and Thursdays until cows were confirmed to have resumed oestrous cycles or until one week before planned start of mating. High intakes pre-calving increased (P < 0.05) the proportion of cows cycling by the third week postpartum (38 {\textpm} 8\%) compared with a low pre-calving intake (13 {\textpm} 6\%). There was a tendency (P = 0.07) for a reduced mean PPAI in the high (29.7 {\textpm} 2.6 days) versus low (33.4 {\textpm} 2.3 days) pre-calving intake treatments, among cows that initiated oestrous cycles during the experimental period. Post-calving intake did not affect PPAI (P = 0.4), nor was an interaction detected. Body condition score (BCS) at all time points in this study, including before treatments were initiated, was negatively correlated with PPAI (P < 0.05). In contrast, PPAI was not associated (P > 0.1) with changes in BCS during the pre- or post-calving periods, or with milk production characteristics. In this study, resumption of oestrous cycling post partum was strongly linked to pre-existing differences in BCS, and modified by pre-calving pasture intake, but not influenced by feeding intakes or milk production characteristics in early lactation.
KEYWORDS: anoestrus; nutrition; dairy cow. },
	issn = {1176-5283},
	author = {Burke CR and Roche JR and Aspin PW and Lee JM and Taufa VK}
}
@conference {41570,
	title = {Effects of feeding level for four weeks precalving on milk production is small and dependent on level of feeding in early lactation},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {215-220},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {The aim was to quantify the relationship between pre- and postcalving level of feeding and their effect on milk production. Sixty-eight multiparous dairy cows were randomly allocated to two levels of pasture feeding (Low and High; 4.8 and 11.9 kg DM/day) for 29 {\textpm} 7.7 days precalving. At calving, cows were randomly allocated (within precalving levels) to two levels of pasture feeding (Low and High; 8.6 and 13.5 kg DM/day) for 35 days postcalving. Daily milk yields were recorded and fat, protein and lactose concentrations determined on 2 days each week for 5 weeks postcalving, and once weekly for an additional 10 weeks post treatment. Body condition score (BCS) at calving was 4.2 and 4.7 for precalving Low and High treatment groups, respectively. Precalving restriction reduced milk fat production by 8.4\% during the first five weeks postcalving, but these differences were not evident subsequently. Postcalving feed restriction reduced yields of milk, fat and protein by 25, 21 and 28\%, respectively, during the first five weeks postcalving. Decreased (P < 0.05) yields of milk, fat and protein (12, 10 and 9\%, respectively) were also evident for ten weeks after the feed restriction finished. There was a trend towards a treatment interaction (P = 0.13) in milksolids (MS) production during the first five weeks of lactation between pre- and postcalving level of feeding. High- High cows produced 7.1 kg more MS than Low-High cows, but there was no effect of precalving level of feeding in cows that were restricted postcalving. Results confirm that level of feeding postcalving influences the milk production effect of precalving feeding. Nevertheless the effect of precalving energy intake on postcalving milk production is small.
KEYWORDS: transition cow; pasture; dry matter intake. },
	issn = {1176-5283},
	author = {Roche JR and Kolver ES and Lee JM and Aspin PW and Burke CR and Taylor P and Napper AR}
}
