@article {3672, title = {Persistency and lactation curves modelled using nonlinear random regression in dairy cows milked once a day}, journal = {New Zealand Journal of Animal Science and Production}, volume = {80}, year = {2020}, month = {09/2020}, pages = {131-136}, address = {Online}, abstract = {Modelling lactation curves of dairy cows is important for improved feed management and breeding decisions. The objectives of this study were to compare measures of lactation persistency obtained from the modelling of lactation curves for daily yields of milk, fat and protein using a nonlinear random regression model in dairy cows milked once a day under grazing conditions. A total of 1,955 monthly herd-test records of milk, fat and protein from 55 Holstein-Friesian (F), 64 Jersey (J), and 123 F{\texttimes}J crossbreds of different lactations were used to obtain lactation curves for each cow using a random regression model with the Wood function. Three measures of persistency were calculated based on ratios of yields and compared with persistency calculated based on parameters of the Wood function. Jersey cows in lactation 3 had the greatest persistency for all persistency measures. In first-lactation cows, there were no significant breed differences in persistency. Persistency measures were strongly correlated with each other (r>=0.97; P<0.001). The conclusion from this study is that parameters of the lactation curve (peak yield, day of peak and persistency) can be precisely estimated using the random regression model with the Wood function. Keywords: modelling; lactation curve; persistency; once-a-day milking}, issn = {1176-5283}, author = {Jiang H and Hickson RE and Woods OT and Morandeau M and Burke JL and Correa-Luna M and Donaghy DJ and Lopez-villalobos N} } @article {3672, title = {Genetic parameters for milk urea concentration and milk traits in New Zealand grazing dairy cattle}, journal = {New Zealand Journal of Animal Science and Production}, volume = {78}, year = {2018}, month = {07/2018}, pages = {56-61}, address = {Lincoln}, abstract = {The aim of this study was to estimate genetic parameters for milk urea (MU), yields of milk (MY), fat (FY), crude protein (CPY) and lactose (LY), concentrations of fat (FP), crude protein (CPP) and lactose (LP) and efficiency of crude protein utilisation (ECPU) in grazing dairy cows. Data consisted of 1284 herd-test records of milk traits and MU from 468 mixed-breed cows in two herds. Univariate and bivariate repeatability animal models were used to estimate heritabilities (h2) and genetic (rG) and phenotypic (rP) correlations among the traits. Estimates of h2 for MU and ECPU were 0.24 and 0.11, whereas h2 estimates for MY, FY, CPY and LY ranged from 0.10 to 0.20. Estimates of h2 for FP, CPP and LP were 0.37, 0.59 and 0.19, respectively. The estimates of rP for MU with other traits were near zero. The rG of MU with MY (0.38), and of MU with LY (0.31) were positive and significant (P<0.01) whereas the rG of MU with FP (-0.80), CPP (-0.66) and LP (-0.76) were negative and significant (P<0.01). The rG between MU and ECPU was -0.09. These estimates of genetic parameters can be used to predict genetic responses to selection for reduction of MU.}, issn = {1176-5283}, author = {Lopez-villalobos N and CorreaLuna M and Burke JL and Sneddon NW and Schultz MM and Donaghy DJ and Kemp PD} } @conference {3672, title = {Culling reasons in once-a-day milking cows and differences in production and type traits between retained and culled cows}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {77}, year = {2017}, month = {06/2017}, pages = {200-204}, address = {Rotorua}, abstract = {The aim of this study was to investigate the culling reasons in cows milked once-a-day (OAD), evaluating the differences of production, fertility and traits other than production (TOP) between retained and culled cows. Cows in different lactations from Massey University Dairy 1 were scored for 18 TOP for three consecutive seasons from 2013 to 2015. Herd-test records were used to estimate milk yield (MY), fat yield (FY), protein yield (PY) and somatic cell score (SCS). Low fertility, poor udder conforma-tion and low production were the main reasons for culling in all seasons. Overall, culled cows had a lower MY (3534{\textpm}56 kg), FY (173.5{\textpm}2.8 kg), PY (138.5{\textpm}2.1 kg) and higher SCS (6.41{\textpm}0.09) than retained cows (MY = 4006{\textpm}41 kg; FY = 204.7{\textpm}1.9 kg; PY = 160.6{\textpm}1.5; SCS = 6.19{\textpm}0.06). Culled cows had a poorer adaptability to milking (7.02 {\textpm} 0.04) and poorer farmer{\textquoteright}s overall opin-ion (7.62{\textpm}0.06) than retained cows (7.23{\textpm}0.03 and 7.89{\textpm}0.04, respectively). Moreover, culled cows had a weaker udder support (5.56), weaker front udder (5.48) and lower rear udder (6.01) than retained cows (6.19, 5.85 and 6.25, respectively). These traits might have a higher influence on the culling decisions of OAD dairy farms than the age and production worth of cows.}, issn = {1176-5283}, author = {Rocha JF and Lopez-Villalobos N and Burke JL} } @conference {3672, title = {Estimation of genetic parameters for milk yield traits at different herd production levels in cows milked once- or twice-daily in New Zealand}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {49-53}, address = {Adelaide}, abstract = {The objective of this study was to estimate genetic parameters for lactation yields of milk (MY), fat (FY) and protein (PY) for cows milked either once- (OAD) or twice-a-day (TAD) at different production levels (PL), calculated as average milk solids yield (FY + PY) for dairy cattle in New Zealand. Lactation records of 124,620 and 194,631 cows from 298 and 350 herds milked OAD and TAD, respectively were used. Heritiabilities (h2) were lower in low PL herds milked OAD compared to low PL herds milked TAD (0.11-0.18 vs. 0.22-0.37). Across PL, h2 for MY at medium and high PL were greater than 0.30 at both MF, while for FY and PY, those values were less than 0.30. Genetic correlations (rG) between MY and PY were greater (>0.70) compared to rG between FY and any of the other traits (<0.65). The lowest rG was observed between MY and FY at low PL (0.09{\textpm}0.087). In conclusion, lower h2 at low PL from cows milked OAD reveal unequal genetic expression of milk traits genes compared to higher PL. Ignoring the heterogeneity of variance in the genetic evaluation could result in systematic inaccuracies and biases in the estimation of breeding values for cows milked OAD.}, issn = {1176-5283}, author = {Lembeye F and Lopez-Villalobos N and Burke JL and Davis SR} } @conference {3672, title = {Genetics of alternative definitions of feed efficiency in grazing lactating dairy cows}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {38-42}, address = {Adelaide}, abstract = {There has been anecdotal evidence of increasing liver abscessation on bull-beef farms across New Zealand from meat processors for more than a decade, but to date, no quantitative data has been published in the field. This study objective was to establish the incidence of liver abscessation in pasture- based beef bulls, the seasonality and breed differences, the impact on carcass weight, and to compare this with published data from feedlot cattle internationally. The study used a database of 137675 bulls slaughtered in the South Island between 2000-2005. The database included breed, farm location, carcass weight, liver abscess presence and abscess grading score (absent, mild, moderate, severe). The annual incidence of liver abscessation calculated was a mean of 9.5\%. This recorded value is greater than other observed incidences from pasture-based systems and reduced compared with those observed in non-medicated feedlot systems internationally. There were significant variations in all measured parameters across years, and a clear and significant seasonal variation was observed. Incidence of liver abscessation peaked across November- December (11.3 and 11\% respectively) and then declined as the slaughter season progressed. The typical NZ beef industry approach to rearing bulls for slaughter makes it likely that age at slaughter is a key influence on the seasonal incidence rate, with most cattle born in spring and slaughtered after 18 months, suggesting the late spring and summer peak in incidence is due to bulls older than two years. The percentages of abscesses graded were: severe (66.4\%), moderate (12.8\%), and mild (20.7\%). Friesian and dairy crossbreed bulls had an incidence approximately twofold greater than that females beef breeds (10.3\% and 4.7\% respectively). There was a significant difference in the mean carcass weights of bulls graded, with those moderate with abscessation having a mean heavier carcass weight than those graded severe, minor and no abscess.}, issn = {1176-5283}, author = {Hurley AM and Lopez-Villalobos N and McParland S and Lewis E and Kennedy E and O{\textquoteright}Donovan M and Burke JL and Berry DP} } @conference {3672, title = {Estimation of breed and heterosis effects for milk traits and somatic cell scores in cows milked once and twice daily in New Zealand}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {60-63}, address = {Dunedin}, abstract = { Crossbreeding is widely used by famers milking twice-a-day (TAD) to increase farm profitability. Effects of crossbreeding on farm productivity and profitability have not been investigated in farms practicing once-a-day (OAD) milking. The aim of the study was to estimate breed and heterosis effects for lactation length (LL), total yields of milk (MY), fat (FY) and protein (PY) and average somatic cell score (SCS) in cows milked OAD or TAD. Records from 36,276 Friesian (F), 31,560 Jersey (J) and 90,081 crossbred (F{\texttimes}J) cows that calved in spring between 2008 and 2012 were used. Compared to J cows, F cows had a higher MY (657 kg in OAD and 1034 kg in TAD), FY (2.9 kg in OAD and 7.8 kg in TAD), PY (13.6 kg in OAD and 22.4 kg in TAD) and SCS (0.28 in OAD and 0.05 TAD). Lactation length in OAD cows was five days shorter than in TAD cows (P<0.05). These results show a significant interaction between breed and milking frequency for production traits (P<0.001). Expressed as a percentage of the average of parental breeds, first-cross heterosis effects ranged between 4.92 to 6.84\% for production traits, and were similar across milking frequencies. The estimates of breed and heterosis obtained in this study can be used for simulation studies to evaluate the profitability of crossbreeding systems under OAD and TAD milking systems of typical New Zealand dairy farms.}, issn = {1176-5283}, author = {Lembeye F and Lopez-Villalobos N and Burke JL and Davis SR} } @conference {3672, title = {Phenotypic correlations among alternative definitions of feed efficiency in grazing lactating dairy cows across parities and lactation stages}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {34-38}, address = {Dunedin}, abstract = { The objective of this study was to estimate correlations among alternative measures of energy conversion efficiency and energy balance (EB) across parities and lactation stages in grazing lactating dairy cows. Individual measurements of net energy intake (NEI) (n=8,183) from pasture and concentrate from 2,693 lactations on 1,412 cows were available. Residual energy production (REP) was defined as net energy of lactation (NEL) minus predicted energy requirements; energy conversion efficiency (ECE) was defined as NEL divided by NEI; and EB was defined as the difference between NEI and energy required for both maintenance and lactation. Residual energy intake (REI) was defined as NEI minus predicted energy requirements. A strong correlation existed between REI and EB (0.88; P<0.05) for parity three or greater early lactation, weakening in parity one (0.70; P<0.05). These differences in correlations between REI and EB for animals across parities in early lactation, indicated primiparous animals were using body energy for milk production and growth; nevertheless, these strong correlations suggested negative REI animals (i.e., more efficient) are also in more-negative EB. Our findings suggest REI could be a valuable tool for future genetic improvement,}, issn = {1176-5283}, author = {Hurley AM and Lopez-Villalobos N and McParland S and Lewis E and Kennedy E and O{\textquoteright}Donovan M and Burke JL and Berry DP} } @conference {3678, title = {BRIEF COMMUNICATION: Milk production, live weight, body condition and somatic cell score during the first 150 days of lactation in Friesian, Jersey and crossbred cows milked once daily}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {74}, year = {2014}, month = {06/2014}, pages = {46-48}, address = {Napier}, abstract = {Pasture-based dairy farming in New Zealand has predominately been with cows milked twice a day (TAD). However, since the last decades, milking once a day (OAD) has been adopted by some farmers in New Zealand for herd management and lifestyle benefits (Davis 2005)...}, issn = {1176-5283}, author = {Lambeye F and Lopez-Villalobos N and Burke JL and Davis SR} } @conference {78995, title = {In vitro fermentation of [15N-] ryegrass and ruminal digesta of sheep grazing a ryegrass-based pasture in the morning or in the afternoon}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {72}, year = {2012}, month = {Jan}, pages = {100-105}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {

Sheep in many areas of Australia and New Zealand experience periods of variable feed supply. Merino sheep can be bred to be more resilient to this varying feed supply. Resilient sheep lose less live weight when grazing poor quality pasture. However, we do not know if breeding for live weight change genetically affects reproduction. To estimate genetic correlations between live weight change and reproduction we used information from 6,870 fully pedigreed Merino ewes aged two- to four-years-old. Liveweight change was measured during joining (42 days) on low quality pasture and during lactation (130 days) on high quality pasture. Reproduction traits were total weight of lambs born and weaned and binary traits of whether or not a ewe gave birth to, or weaned, a lamb. Genetic correlations between live weight change and reproduction within age were estimated. There were moderate to high genetic correlations between live weight loss during joining and the chance of having and weaning a lamb. All other correlations were low. Therefore, change in live weight during joining affects the chance of having a lamb but not the weight of those lambs.

}, issn = {1176-5283}, author = {Vibart RE and Tavendale MH and Burke JL and Pacheco D} } @conference {75910, title = {The apparent digestibility of palm kernel expeller (PKE) consumed by pasture-fed sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {71}, year = {2011}, month = {Jan}, pages = {223-228}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Invercargill}, abstract = {

Palm kernel expeller (PKE) usage in New Zealand has increased despite little being known about its nutritional role as a supplement in pasture based diets. The chemical composition of PKE is often reported in New Zealand, but the digestibility is not. A digestibility study was conducted with twenty four lambs fed one of four different amounts (0, 15, 30 or 45\%) of their dry matter (DM) intake as PKE, plus molasses pellets (PKEM; 90\% PKE and 10\% molasses) with the remainder of the diet being fresh pasture. Sheep were fed at either maintenance or ad libitum during two experimental periods, that differed in pasture quality. Digestibilities were extrapolated linearly to estimate digestible energy concentration and the apparent digestibility of DM, crude protein, neutral detergent fibre and gross energy at any intakes for a diet consisting of 100\% PKEM. Overall, the estimated apparent digestibility of DM, crude protein, neutral detergent fibre and gross energy for PKEM at intakes of 670 and 1,214 gDM/lamb/day were 63.0, 52.0, 67.0 and 64.0\%, respectively. The values estimated for digestible energy concentration (MJ/kgDM) of PKEM ranged between 12.4-12.7, from which values for metabolisable energy concentration of 10.2 and 10.5 MJME/kgDM could be calculated.

}, issn = {1176-5283}, author = {Burke JL and Dias FN and Pacheco D and Lopez-Villalobos N and Holmes CW} } @conference {75912, title = {Ruminal fermentation characteristics from sheep offered a fresh grazing allocation of a ryegrass-based pasture either in the morning or in the afternoon}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {71}, year = {2011}, month = {Jan}, pages = {234-239}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Invercargill}, abstract = {Eight rumen-fistulated wethers were used to examine the effects of PM (16:00 h) versus AM (08:00 h) allocation of spring herbage from pasture on aspects of ruminal metabolism that lead to increased utilisation of nutrients. The experimental period consisted of two phases; adaptation to diets and intensive sampling. During the adaptation phase, total volatile fatty acids (VFA) and ammonia concentrations were greater for the PM group, whereas the ratio of non-glucogenic to glucogenic VFA did not differ. These results suggest greater fermentation from forage that had similar concentrations of crude protein, neutral detergent fibre, and water soluble carbohydrates, but greater organic matter digestibility (84.1 vs. 82.3\%). During the intensive sampling phase, the mean total VFA and ammonia concentrations did not differ among groups, but the 24-hour pattern varied considerably for all variables measured. Unseasonal weather conditions during the trial were associated with smaller differences in water soluble carbohydrate accumulation than expected. Based on our results, at least four hours of sunshine were needed to obtain diurnal differences greater than 20 g per kg herbage DM. The implication of these findings on the implementation of nutritional management strategies warrants further investigation.}, issn = {1176-5283}, author = {Vibart RE and Burke JL and Pacheco D} } @conference {69463, title = {Effect of white clover containing high or low concentrations of water-soluble carbohydrate on metabolic indicators of protein degradationin the rumen of dairy cattle}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {70}, year = {2010}, month = {Jun}, pages = {23-28}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {White clover has high nutritive value, but contains excess protein relative to energy, leading to the wasteful excretion of nitrogen (N) by animals. Five cycles of divergent selection has resulted in white clover lines having high (HS) or low (LS) concentrations of water-soluble carbohydrate. A grazing trial was carried out to evaluate the effect of this selection on protein utilization, using skatole and indole concentrations in the milkfat as metabolic indicators for nitrogen utilisation in the rumen. Skatole and indole arise in the rumen from the degradation of the amino acid tryptophan, and rapidly accumulate in milkfat of lactating animals fed diets rich in soluble and degradable protein. Skatole and indole concentrations were both significantly (P <0.001) lower in cows fed HS clover (356 and 84 ng/g milkfat for skatole and indole, respectively) compared to those fed the LS white clover diet (800 and 420 ng/g milkfat, respectively) suggesting protein utilisation of the HS clover was improved. Although not statistically significant in this short-term study, the trends to lower concentrations of milk urea-nitrogen and urinary-N, and the nitrogen:creatine ratio for the HS clover were in the direction expected and warrant further investigation under longer-term feeding.}, issn = {1176-5283}, author = {Higgs RJ and Cosgrove GP and Burke JL and Lane GA and Pacheco D and Fraser K and Death AF and Ford JL} } @conference {60975, title = {Urinary nitrogen excretion from cows at different stage of lactation grazing different ryegrass cultivars during spring or autumn}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {69}, year = {2009}, month = {Jun}, pages = {196-200}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {The effects of season (spring or autumn) and stage of lactation (early or late) on the partitioning of dietary nitrogen (N) between milk and urine were measured in experiments in which cows grazed forages with putative differences in the ratio of water soluble carbohydrates (WSC) to crude protein (CP). Sixty cows (n = 30 for each stage of lactation) grazed one of three forages during spring and autumn. Forage treatments consisted of a {\textquoteright}standard{\textquoteright} perennial ryegrass (STG) and two ryegrasses with high WSC concentrations: a perennial {\textquoteright}high sugar{\textquoteright} ryegrass (HSG), and an annual ryegrass (IRG). In spring, grass type had a significant effect on the estimated urinary N excretion. Both the HSG and STG resulted in greater N excretion compared to the IRG, due to the low CP concentration in this forage in one of the grazing periods. In autumn, cows grazing STG excreted less urinary N than both HSG and IRG. In both seasons, cows in early lactation secreted more N into milk but were not different in N excretion. In early lactation cows, the extra N in milk was only a small proportion of the potential N intake arising from higher CP content in autumn grasses. }, issn = {1176-5283}, author = {Pacheco D and Lowe K and Burke JL and Cosgrove GP} } @conference {60971, title = {The variation in methane emissions from sheep and cattle is not explained by the chemical composition of ryegrass}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {69}, year = {2009}, month = {Jun}, pages = {174-178}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {A data base of over 3,000 ruminant methane emission records from individual animals used to compile New Zealand{\textquoteright}s greenhouse gas inventory, shows substantial variation in CH4 yields (g/kg dry matter intake (DMI)) within and between forage types. Multiple regression analyses were undertaken using datasets from sheep and cattle fed fresh ryegrass to determine the extent to which variation in CH4 yields could be explained by ryegrass chemical composition. Methane was measured using the SF6 marker dilution technique with sheep and cattle, and also directly by respiration calorimetry from sheep. Data from sheep showed a similar average CH4 yield from both techniques, but there was more variation in SF6 data (23.4 {\textpm} 5.73) than from calorimetry (23.1 {\textpm} 2.89). Cattle CH4 yields averaged 19.1 {\textpm} 3.70 g/kg DMI. Multiple regression analysis of sheep data showed pasture chemical composition accounted for <2\% of the variation determined by SF6 and 20\% of the variation from calorimetry. Only 13\% of the variation in yield from cattle was explained by ryegrass composition, so the majority of variance (>80\%) was not explained. We suggest the variation in CH4 emissions is affected by digestive characteristics of individual animals, and interactions with forage physical and chemical components. }, issn = {1176-5283}, author = {Hammond KJ and Muetzel S and Waghorn GC and Pinares-Patino CS and Burke JL and Hoskin SO} } @conference {42058, title = {The effect of palm kernel expeller as a supplement for grazing dairy cows at the end of lactation}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {68}, year = {2008}, month = {Jan}, pages = {111-112}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Brisbane, Australia}, abstract = {Palm kernel expeller (PKE) is a solid byproduct from the palm oil. In New Zealand it is used as a supplementary feed on dairy farms to fill short term pasture deficits and according to MAF (2007), over 350,000 tonnes of PKE was imported into New Zealand during 2007. Despite its growing use as a feedstuff for ruminants in New Zealand, information is scarce about the nutritional value of PKE and ...Continued }, issn = {1176-5283}, author = {Dias FN and Burke JL and Pacheco D and Holmes CW} } @conference {41864, title = {Clover-rich diets and production, behaviour and nutrient use by cows in late lactation}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {66}, year = {2006}, month = {Jan}, pages = {42-49}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Napier}, abstract = {The nutritional value of legumes for high milk production is seldom captured because grazed dairy pastures in NZ typically contain insufficient legume to satisfy the cows{\textquoteright} requirements. This paper reports interim results from a project investigating novel methods of forage presentation to cows, to enhance the contribution of legume to their diet. Four groups of spring-calving cows (n=5) in late-lactation were allocated to four treatments in a balanced, cross-over design. Two treatments consisted of spatial and temporal arrangements of grass and white clover allocated to cows as follows: i) continuous free access to grass and white clover growing separately as side-by-side monocultures (G/C) and ii) grass-only at {\textquoteleft}night{\textquoteleft} between the afternoon and morning milking and clover-only during the {\textquoteleft}day{\textquoteleft} between morning and afternoon milking (GnCd). These were compared against controls of iii) a typical mixed ryegrass-white clover pasture (Mix; an industry standard) and iv) a ryegrass-only pasture (Grass; a forage standard). Cows grazed each treatment for 8 days before moving to the next treatment in the pre-determined sequence. Measurements included milk production and composition, the time spent grazing during the day and the night (separately for grass and white clover in G/C) and the concentrations in the milk of skatole and indole, as metabolic indicators of nutrient acquisition and utilisation in the contrasting forage treatments. Cows offered G/C or GnCd produced 19.4 and 17.9 kg milk/cow/day, respectively, compared with 15.0 and 14.6 kg/cow/day when offered Mix or Grass, respectively (P=0.01, SEM=0.74). The diurnal distribution of grazing was influenced by pasture treatment (treatment x time interaction P <0.001). Cows on G/C grazed proportionately more at {\textquoteleft}night{\textquoteright} and cows on GnCd proportionately less at {\textquoteleft}night{\textquoteright} compared with Grass or Mix. GnCd constrained the cows to spend less time grazing clover than those offered G/C (245 vs. 408 mins grazing clover during 24 hrs) and more time grazing grass (253 vs. 105 mins in 24 hrs). The apparent {\textquoteleft}restriction{\textquoteleft} in GnCd to grazing clover-only during the day did not significantly reduce milk yield compared with G/C. The spatial and temporal allocations of grass and clover affected the concentrations of indolic compounds in PM and AM milk, suggesting there is scope to improve the efficiency of protein utilisation in the rumen. }, issn = {1176-5283}, author = {Cosgrove GP and Burke JL and Death AF and Lane GA and Fraser K and Pacheco D and Parsons AJ} } @conference {41613, title = {In vitro production of volatile fatty acids from forages}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {66}, year = {2006}, month = {Jan}, pages = {50-54}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Napier}, abstract = {Volatile fatty acid (VFA) production from a range of fresh forages was measured in vitro over 24 hours (h). The forages comprised temperate and tropical grasses, legumes (including some containing condensed tannins; CT), herbs and silages, all of which were minced to resemble chewed forage and incubated in buffered media. Volatile fatty acid concentrations were measured in triplicate for each feed at 0, 6, 12 and 24 h. On average, VFA yields were 131, 226 and 311 mg/g dry matter (DM) between 0 - 6, 0 - 12 and 0 - 24 h, and the highest yields were from legumes (384 mg/g DM) and lowest from plantain (176 mg/g DM) after 24 h. Legumes containing CT produced 28\% less VFA than other legumes. The acetate + butyrate:propionate (A+B:P) ratio showed a substantial difference between forage types, ranging from an average of 2.5 (legumes) to 3.5 (tropical grasses) after 6 h, but differences between forage types diminished after 24 h. Multiple regression analysis showed a weak inverse relationship with NDF (neutral detergent fibre) after 6 h, but there was no clear relationship with particle size, chemical composition or digestion rates at 12 and 24 h. }, issn = {1176-5283}, author = {Burke JL and Waghorn GC and Brookes IM and Chaves AV and Attwood GT} } @conference {41911, title = {A simple HPLC method for measuring sulfate in ultra filtered sheep plasma}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {66}, year = {2006}, month = {Jan}, pages = {284-289}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Napier}, abstract = {Plasma sulfate concentration is a useful indicator of sulfur amino acid oxidation. Measurement of sulfate in water and other fluids has been made by turbidimetric, ultra-violet (UV) absorption or ion chromatography HPLC methods. The turbidimetric method is variable and suffers from interferences and both turbidimetric and UV methods are less sensitive than ion chromatography. We describe a quick and simple HPLC method, where sample preparation is a centrifugal filtration and the sulfate measurement is by single column HPLC using one buffer at a constant flow rate. Recoveries from spiked samples were 99.5 \% (RSD 1.8 \%) and the RSD of repeated standards over 6 weeks was 0.7 \%. Using this method, we measured plasma sulfate levels in both growing lambs with intestinal parasites and in sheep fed fresh Lotus corniculatus containing condensed tannins (CT) or other fresh forages. The CT in Lotus corniculatus decreased (P < 0.05) plasma sulfate concentration while parasite infection did not (P > 0.05). Our method provided quick and reliable data that could be transferable for measuring sulfate in blood, serum and other biological fluids and could be used as a biomarker of whole body sulfate status under various physiological conditions in farm animals. }, issn = {1176-5283}, author = {Sinclair BR and Tavendale MH and Bermingham EN and Burke JL and McNabb WC and Roy NC} } @conference {41853, title = {Digestion kinetics of New Zealand native flax}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {65}, year = {2005}, month = {Jan}, pages = {367-371}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {This experiment compares the nutritive value of New Zealand native flax, Phormium tenax, by-products i.e. leaves (L), butts (B), thrash-stripped fibre (F) and green matter (G), with white clover (WC) via digestion kinetics derived from in vitro and in sacco incubations. The WC had a high nutritive quality (11.1 MJME/kg DM, CP 28\% DM), G a moderate (10.1 MJME/kg DM, CP 9\% DM), and L, B, F were of very low nutritive quality (< 8 MJME/kg DM, CP < 6 \% DM). After 24 hours, 96, 76, 47, 47, and 30 \% of the DM was degraded for WC, G, L, B and F, respectively (P < 0.001). The degradation rates (\%/h) of digestible DM were faster (P < 0.001) for WC (13) and G (11) than B (3.8), L (4.6) and F (2.7). Flax by-products had a net loss of ammonia after 2 (B), 4 (F and L) and 8 hours (G). The proportion of DM converted to VFA by 8 hours was 21 \%, and 14 \% for WC and G respectively, but only 9-10 \% for the other flax by-products (P < 0.001). The feeding model BestFeed{\texttrademark} predicted that G could grow a 500 kg bull at 0.8 kg/day and had potential as a supplement for pasture-fed animals. KEYWORDS: flax; Phormium tenax; in sacco; in vitro; digestion kinetics; nutritive value; forage ration, BestFeed. }, issn = {1176-5283}, author = {Litherland AJ and Layton DL and Burke JL and Corson DC and Peters JS} } @conference {41413, title = {Empirical assessment of the CNCPS model to predict performance of dairy cows fed pasture with silage supplements}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {63}, year = {2003}, month = {Jan}, pages = {91-95}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Queenstown}, abstract = {The goal of this work was to determine the accuracy and utility of the Cornell Net Carbohydrate and Protein System (CNCPS) model to predict milk production from diets based on pasture and forage supplements. Data were obtained from studies in which pasture was complemented with contrasting silages including maize, pasture, sulla, lotus and forage mixtures, comprising 30-40\% of dry matter intake (DMI). Twelve diets were used in this evaluation. DMI, live weight (LW), days in milk, and diet composition were determined during the trials and used as inputs in the model. Across all diets, a significant (P<0.01) relationship existed between predicted and actual values for DMI (r2=0.63), milk yield (r2=0.64) and LW change (r2=0.57) but there were still large unexplained sources of variation and the slopes of the regression lines were significantly (P<0.01) different than 1. No significant mean bias was observed for any of the variables, but the slope of residual differences against predicted values was significantly different from zero (P<0.01 for milk yield and LW change; P<0.06 for DMI). The results indicate a satisfactory prediction of milk production when cows are neither gaining nor losing weight, but that a systematic bias exists probably because of the CNCPS model{\textquoteright}s failure to account for nutrient partitioning. }, issn = {1176-5283}, author = {Chaves AV and Brookes IM and Burke JL and Waghorn GC and Woodward SL} } @conference {41337, title = {An evaluation of sulla (Hedysarum coronarium) with pasture, white clover and lucerne for lambs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {62}, year = {2002}, month = {Jan}, pages = {152-156}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {Pasture-based diets restrict animal performance, due to limitations in voluntary feed intake and release of nutrients during digestion failing to meet nutrient requirements. Opportunities for improving the efficiency of pasture utilisation include the addition of a soluble carbohydrate source to enable an improved capture of ammonia by rumen bacteria, or the inclusion of condensed tannins (CT) to reduce protein degradation. A feed evaluation trial was conducted at AgResearch Grasslands to investigate the ability of sulla, a forage containing high concentrations of soluble carbohydrate and CT, to complement pasture and legume species. Fifty-six weaned ram lambs were allocated to seven diets: pasture (80\% ryegrass and 20\% white clover), white clover, lucerne, sulla, and 50:50 mixtures (DM basis) of pasture:sulla, white clover:sulla and lucerne:sulla. Lambs fed sulla, white clover, white clover:sulla and lucerne:sulla had the most rapid daily gains (256-263 g/day) while lambs fed pasture gained 105 g/day, respectively. Wool growth was influenced by diet. Sulla added to pasture, white clover and lucerne diets significantly reduced rumen ammonia concentrations and acetate:propionate ratios in lambs. Lamb performance can be improved by combining sulla with pasture and lucerne, and rumen parameters can be used to explain animal performance differences. }, issn = {1176-5283}, author = {Burke JL and Waghorn GC and Brookes IM} } @conference {41365, title = {Improving animal performance using forage-based diets}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {62}, year = {2002}, month = {Jan}, pages = {267-272}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {

New Zealand livestock systems are based on ryegrass dominant pastures, but they are unable to maximise animal production. Limitations of ryegrass-based pastures are reviewed, and opportunities for using alternative forage species to complement pasture and improve animal production are discussed. Ryegrass pastures have low dry matter contents and high fibre concentrations which restrict feed intake so animal energy requirements are often not met. High crude protein (CP) concentrations in spring and rapid proteolysis in the rumen produces excess ammonia which must be excreted, whereas summer pastures contain insufficient CP. Chicory, red clover, lotus species, sulla, lucerne and maize silage are examples of forages that can complement ryegrass to improve animal performance. More information is needed to define digestion and fermentation of fresh forages in the rumen, but in vitro and in sacco techniques have been used to evaluate these parameters for grasses, legumes, herbs and silages. This information with feed composition data will be used in computer simulations to predict forage mixtures able to complement pasture at different times of the year. The challenge will be to complement the changing ryegrass pastures with other forages to improve animal welfare, productivity and profit.

}, issn = {1176-5283}, author = {Burke JL and Waghorn GC and Chaves AV} } @conference {41231, title = {Digestion kinetics of mature grasses}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {61}, year = {2001}, month = {Jan}, pages = {8-12}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Digestion kinetics were measured for mature (green and non-senescent) components of five grass species using in sacco and in vitro incubations to define rates of degradation and nutrient release. The data will be incorporated into a dairy nutrition simulation model to identify limitations in nutrient supply to cows grazing mature pasture in late spring. Perennial ryegrass, tall fescue, Yorkshire fog, phalaris and paspalum were hand separated into leaf, stem and inflorescence for incubations. Percentages of fibre (NDF) in DM fractions ranged from 50-69\% (leaf), 63-75\% (stem) and 50-68\% (inflorescence). Crude protein concentrations in the DM of the respective fractions were 7.5-23.7\%, 3.8-8.3\% and 7.9-12.3\%. Soluble DM (\% of the total) determined after mincing accounted for 31-53\% of leaf, 26-55\% of stem and 20-48\% of inflorescence, and fractional (h-1) degradation of the insoluble DM was very slow, ranging from 0.034-0.113 (leaf), 0.025-0.036 (stem) and 0.033-0.072 (inflorescence). After 24 hours of in vitro incubation plant nitrogen content become limiting for fermentation in most instances. }, issn = {1176-5283}, author = {Chaves AV and Waghorn GC and Brookes IM and Burke JL} } @conference {41147, title = {Formulating total mixed rations from forages - defining the digestion kinetics of contrasting species}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {60}, year = {2000}, month = {Jan}, pages = {9-14}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {The work described here is the first step in formulating forage-based TMR rations for dairy cows, based on digestion kinetics derived from in vitro and in sacco incubations. Kinetic information has been obtained from 23 contrasting fresh and conserved forages species, including temperate and tropical grass species, legumes (including Lotus spp. containing condensed tannins), herbs, silages, lucerne hay and maize grain. All forages were minced to a particle size similar to chewed material. Estimates of DM solubility (\% DM) and fractional dry matter degradation rates (h-1) determined by in sacco incubations include: white clover (39\%, 0.195), perennial ryegrass (45\%, 0.114), tall fescue (46.8\%, 0.051), paspalum (27\%, 0.068), sulla (51.4\%, 0.121), chicory (41.8\%, 0.260), pasture silage (41\%, 0.083), maize silage (28\%, 0.042). In vitro incubations resulted in five-fold differences between forages in net ammonia release, 2-3 fold differences in volatile fatty acid yield and a three-fold difference in acetate:propionate ratio. The data will be used in simulation models to identify optimal forage mixtures for meeting the nutritional needs of high-producing dairy cows. }, issn = {1176-5283}, author = {Burke JL and Waghorn GC and Brookes IM and Attwood GT and Kolver ES} } @conference {41146, title = {Preparation of fresh forages for incubation and prediction of nutritive value}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {60}, year = {2000}, month = {Jan}, pages = {5-8}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {In vitro and in sacco digestion offers a rapid and inexpensive method for evaluating nutritive value of ruminant feedstuffs. This study compared the conventional freeze dried and ground (FD) preparation with chopping to 6-mm lengths (C) and mincing (M) to represent chewed forage. In sacco and in vitro comparisons were made with perennial ryegrass (RG), white clover (WC) and Lotus corniculatus (LC). The mean proportions of large (>1.0mm) and soluble dry matter (DM) for the three forages were: M, 0.38 and 0.44; C, 0.76 and 0.21; FD, 0.35 and 0.34 respectively. Disappearance of DM and crude protein (CP) during the first 12 hours of rumen incubation was substantially lower for chopped forages. Minimal lag times before the onset of protein degradation were observed following mincing. Yields of ammonia from proteolysis in in vitro incubations were lowest for C and usually highest for M preparations. Preparation also affected yield but not proportions of VFA. These data show that ranking of forages for digestibility is affected by preparation and mincing appears to be a more suitable preparation for assays than chopping and freeze drying and grinding. }, issn = {1176-5283}, author = {Barrell LG and Burke JL and Waghorn GC and Attwood GT and Brookes IM} }