@conference {41310,
	title = {Effects of time-of-calving on dairy production: a farmlet study},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {62},
	year = {2002},
	month = {Jan},
	pages = {42-43},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {Most dairy cows in New Zealand are calved just prior to spring in order to maximise pasture utilisation. This practice is associated with marked irregularities in the volume and composition of milk supplied to factories, which is a major limitation of seasonally-calving, pasture-based dairying systems. The need to accommodate peak milk flow means that manufacturing plants are underutilised for most of the season. Further, changes to milk composition can make it difficult to manufacture dairy products of high quality during some parts of the season, which necessitates the storage of product to meet out-of-season demand.
Such irregularities are caused by a number of factors, including nutritional factors associated with the changing quality and availability of pasture, and physiological and hormonal factors associated with the stage of lactation of the cows (Auldist et al., 1997). One way of manipulating the lactation curve of the cows may, therefore, be to adjust the time of the year at which calving occurs. A previous study in New Zealand showed that autumn calving herds could be as profitable as spring calving herds (Garcia et al., 1998). In that study, nutritional demands were matched with pasture availability by adjusting stocking rate and feeding varying amounts of pasture and maize silage when required. A premium for winter milk was also applied.
The current study was designed to investigate the effects of calving at four different times of the year on milk production in farmlet systems which were otherwise similar in stocking rate and other farm management variables. },
	issn = {1176-5283},
	author = {Audlist MJ and MacDonald KA and Thomson NA and Coulter M and Lancaster JAS and Penno JW}
}
@conference {41329,
	title = {A whole-farm model applied to a dairy system},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {62},
	year = {2002},
	month = {Jan},
	pages = {120-123},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {The complex interactions between the biological, physical and management aspects of a farm can be represented mathematically using a computer model. A whole-farm model has been developed that links published sub-models for cow metabolism together with climate-driven pasture models, in a framework that allows for different management options. The model framework is written in VisualWorks Smalltalk, with submodels written in several programming languages linked to the framework using Microsoft COM protocol. Predictions of the whole-farm model have been compared with pasture and animal production data obtained from a dairy system trial at Dexcel in the Waikato. The system consisted of a herd of 19 cows, at a stocking rate of 3.2 cows/ha. The Whole Farm Model was used with Baldwin{\textquoteleft}s MOLLY cow model of metabolism, the McCall (1984) model of pasture growth, daily climate data and a management policy whereby daily activities on the farm were enacted by the framework. These activities included, for example, assignment of paddock for grazing, closure and cutting of paddocks for conservation, calving and drying off dates of each cow, and supplement feeding. At the end of each season the whole-farm model predicted 75\% of pasture growth compared with observed values assessed by visual assessment, 98\% of milk yield and 98\% of cow live weight. In addition to annual production by the whole farmlet, the whole-farm model can simulate individual animal and paddock production on a monthly and daily basis, so that patterns of change can be compared over the whole season. The whole-farm model is being used as a tool to design and analyse new dairy farm systems. },
	issn = {1176-5283},
	author = {Wastney ME and Palliser CC and Lile JA and MacDonald KA and Penno JW and Bright KP}
}
@conference {41294,
	title = {Adapting the MOLLY cow model to fit production data from New Zealand animals},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {61},
	year = {2001},
	month = {Jan},
	pages = {234-236},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {To assist in the planning of farm systems trials, Dexcel is developing a computer model of a pasture-based, rotationally grazed dairy system. The model includes published component models (or submodels) for cow metabolism and pasture growth, as well as climate and management information. It is currently being evaluated against production data obtained from the Whole Farm Efficiency Trial at Dexcel No 2 Dairy. The cow component being used is MOLLY, a dynamic model based on the underlying processes of ruminant digestion and metabolism. The parameters of MOLLY are based on animals that are efficient on high-energy diets. To make the computer model more accurate as a predictive tool for use in NZ, some of the parameters of the MOLLY submodel have been adjusted to fit the production data of NZ dairy cows on pasture, namely bodyweight changes and daily milk yields. MOLLY initially under-predicted by approximately 20\% the body weight of older cows (>4 years) for the pre-calving and early lactation periods. Resetting some parameters in MOLLY significantly improved the prediction of these bodyweight changes: to 2\% for the pre-calving period and 14\% for early lactation. Milk yield per cow was under-predicted in early lactation by MOLLY but the fit for each cow was improved by entering the observed peak daily milk value, although further fitting is required. We conclude that MOLLY is suitable for use as a research tool to gain insights into changes in metabolism of NZ cows grazed on pasture.},
	issn = {1176-5283},
	author = {Palliser CC and Bright KP and MacDonald KA and Penno JW and Wastney ME}
}
@conference {41272,
	title = {Magnesium supplementation of lactating dairy cows in the summer and autumn},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {61},
	year = {2001},
	month = {Jan},
	pages = {148-151},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {A series of three trials were established with 188 lactating dairy cows which were supplemented daily with either 0, 10 or 20 g Magnesium (Mg) during 18 weeks from January to May. Cows in each trial were allocated to treatments randomly in a cross-over design with each treatment lasting 2 weeks. This design was replicated three times during the 18 weeks. There was no treatment effect on serum Mg or milksolids (MS) production, (0.82, 0.82 \& 0.83 mmol/l or 0.78, 0.79 \& 0.77 kg MS/cow/day for 0, 10 \& 20 g Mg, respectively; averaged across all trials) and there were no farmlet-by-treatment interactions. Based on visual assessments of pasture intakes and pasture mineral analysis, mean pasture Mg intakes during all three trials ranged from 23 to 35g Mg/cow/day (SEM 1.14). Urine Mg-creatinine ratio of 50 cows during Trial 3 indicated that the urinary Mg concentration increased linearly with increasing dietary Mg (1.38, 1.87, 2.01 for the 0, 10 and 20 g treatments, respectively; SED 0.175). Trial three results suggest that Mg surplus to requirement was being voided by the cow and that it is unlikely that even at the higher stocking rates, a milk production response to Mg supplementation will occur in the summer/early-autumn period when Mg in diet is >0.18\%. },
	issn = {1176-5283},
	author = {MacDonald KA and Penno JW and Verkerk GA and Jago J and Dow BW}
}
@conference {41293,
	title = {Toward a predictive model of supplementary feeding response from grazing dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {61},
	year = {2001},
	month = {Jan},
	pages = {229-233},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Many experiments have measured the responses of grazing dairy cows to supplementary feeds, but few have studied the reasons for the large differences in responses between experiments. Data derived from two trials, in which supplementary feeds of either maize grain or a nutritionally balancing ration were offered to cows in early, mid, and late lactation in each of spring, summer, autumn and winter, were used to calculate the marginal milksolids responses to supplements. The data set created was subject to multiple regression analysis in an attempt to quantify the effect of the different variables on the magnitude of the response to supplementary feeds. The factor that was of greatest importance was the relative feed deficit (RFD) of the cows measured by the reduction in milksolids yield (kg MS/cow/day) of the respective control groups that had occurred when the restricted feeding treatments had been imposed. Total marginal milksolids responses were greatest when severe feed restrictions, relative to current feed demand, resulted in large reductions in milksolids yield of the control groups. Total marginal milksolids response increased (P<0.01) by 0.9g MS/MJME offered as supplement per 0.1 kg MS/cow/day RFD. Total marginal milksolids responses also declined (P<0.01) by 0.2 g MS/MJME offered as supplement as pasture allowance increased by 10 MJME/cow/day. },
	issn = {1176-5283},
	author = {Penno JW and MacDonald KA and Holmes CW}
}
@conference {41209,
	title = {The effect of pasture silage quality on milk production and liveweight gain of dairy cattle},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {60},
	year = {2000},
	month = {Jan},
	pages = {253-255},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {Farmers in NZ have recently been encouraged to increase the quality of pasture silage they harvest. However, there was no New Zealand information available to ascertain the benefits of improved silage quality when it was offered as a supplement to grazing cows. Identical twin sets were divided into three groups in the winter, spring, summer and autumn during the 1998/99 season. Each group was offered a low pasture allowance and in addition, were offered 3 kg (winter) and 5 kg (spring, summer and autumn) DM/cow/day, of High, Medium and Low-quality pasture silage (nominally 10.4, 9.4 and 8.3 MJ ME/kg DM, respectively) as a supplement to pasture. In spring, summer and autumn offering a high quality silage increased milksolids yield from 1.57 to 1.78, 1.09 to 1.28 and 0.63 to 0.89 kg/cow/day, respectively (P<0.05) relative to cows offered Low-quality silage. There were no consistent live weight responses due to pasture silage quality. The spring, summer and autumn measured milksolids response can be calculated as having a net return (at $3.50/kg MS) of 6.7, 5.1 and 8.3 cents per MJME/kg DM increase. },
	issn = {1176-5283},
	author = {MacDonald KA and Nicholas PK and Kidd JM and Penno JW and Napper AR}
}
@conference {41116,
	title = {Increasing milksolids production with supplementary feeds},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {59},
	year = {1999},
	month = {Jan},
	pages = {188-191},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Four farmlets were established at a stocking rate of 4.41 Friesian cows per hectare to compare rolled maize grain, maize silage and a nutritionally balanced ration as supplementary feeds for grazing dairy cows, for three complete seasons. Supplements were offered whenever it was estimated the herds were eating less than 15 kg DM/cow/day or were leaving a post-grazing residual herbage mass of less than 1800 kg DM/ha. Offering 1.3 to 1.5t DM/cow/year of supplement increased net herbage accumulation from 18.3 to 19.2 t DM/ha, however, this did not result in higher annual herbage intake. The use of rolled maize grain, maize silage, and balanced ration supplements increased production from 1188 kg milksolids (MS)/ha to 1763, 1602, and 1769 ({\textpm}69.6) kg MS/ha/year, with responses of 98, 77, and 99 g MS/kg DM, respectively. The magnitude of the response to the supplementary feed was directly proportional to the increase in metabolisable energy supplied by the supplement. Full lactation responses to supplementary feeds were two fold greater than those measured in short term feeding trials. Responses of 7.5g MS/MJME can be expected over the complete lactation when supplements are offered to dairy cows grazing restricted pasture. },
	issn = {1176-5283},
	author = {Penno JW and McGrath JM and MacDonald KA and Coulter M and Lancaster JAS}
}
@conference {41113,
	title = {Validation of body condition scoring by using ultrasound measurements of subcutaneous fat.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {59},
	year = {1999},
	month = {Jan},
	pages = {177-179},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Visual assessment of body condition score (BCS) is used to aid individual cow and herd management, but the assessment is subjective and does not estimate actual body tissue reserves. Ultrasound (US) measurements of external fat reserves may be more objective. To quantify fat reserves at differing BCS{\textquoteleft}s, fat depth was measured by US on 87 mixed aged Friesian dairy cows on 6 occasions during a year. The US measurements were made at the 12th rib (RIB) and mid-way between the hip and pin bones (HIP). Animals were weighed (LW) and their BCS assessed visually at the same time. Mean BCS was greatest in early summer at 4.5 and lowest in late summer at 3.6. Mean RIB varied from 2.2 mm in mid spring to 3.6 mm in early winter, while mean HIP varied from 1.6 mm in early summer to 4.2 mm in early winter. Changes in BCS and LW were positively correlated. Age and growth in 2 year old animals did not appear to affect this relationship. BCS was positively correlated to both RIB and HIP fat depth. The correlation coefficient varied with time, being smallest in late summer (r = 0.37 \& 0.26 for RIB \& HIP respectively) and greatest in late lactation (r = 0.69 \& 0.82 for RIB \& HIP respectively). The ability of RIB \& HIP measurements to predict BCS was low when BCS was <4.5, but predictability increased as fat depth and body condition increased. Cows at lower scores may deposit or deplete fat internally while having few external fat deposits. Because large changes in liveweight (LW) occurred without changes in BCS, or US, it is possible that fat deposits are internal or intramuscular rather than subcutaneous, and therefore not detectable from external inspection. Since most BCS values are <4.5 for lactating cows, the value of ultrasound to assess fat depots in lactating dairy cows is limited; however it may be of some value with cows of BCS >4.5. },
	issn = {1176-5283},
	author = {MacDonald KA and Verkerk GA and Penno JW}
}
@conference {41001,
	title = {Balancing pasture and maize silage diets for dairy cows using urea, soybean meal or fishmeal},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {102-105},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Four treatment groups of 10 Holstein-Friesian cows were established at the DRC No. 2 dairy in the spring, summer and autumn of 1996/97 to test the efficacy of providing urea, soybean meal or fishmeal supplement to overcome the protein deficiency that occurs when cows are supplemented with large amounts of maize silage.  Pasture allowance was manipulated to achieve an average pasture dry matter (DM) intake of 6.6kg/cow/day for each group.  Treatment groups were supplemented with 75 MJ ME/cow/day as either 7.0kg DM of maize silage, 7.0kg DM of maize silage plus 90g of urea,  5.2kg DM of maize silage plus 1.4kg DM of soybean meal, or 5.8kg DM of maize silage plus 1.0kg DM of fish meal.  The addition of urea as a source of non-protein nitrogen had no effect on milk, milkfat or milk protein production.  Soybean meal increased milk protein production by 0.06kg/cow/day in both summer and autumn (P<0.01). Fishmeal increased milkfat production by 0.07 (P<0.01) and 0.08kg/cow/day (P<0.05) in summer and autumn and increased milk protein by 0.06 (P<0.01), 0.10 (P<0.01) and 0.08kg/cow/day (P<0.001) in spring, summer and autumn, respectively.},
	issn = {1176-5283},
	author = {MacDonald KA and Penno JW and Kolver ES and Carter WAC and Lancaster JAS}
}
@conference {41004,
	title = {The effect of stage of lactation and season on milksolids response to supplementary feeding of dairy cows.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {113-116},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {A factorial design was used to determine the effect of offering cows (n=8) in early, mid, and late lactation 50 MJME/cow/day of rolled maize grain (T2) or a nutritionally balanced supplement (T3) in spring, summer, autumn and winter at a restricted pasture allowance. The average milksolids production of the early, mid and late lactation groups was 1.16, 1.10, and 0.96 kg MS/cow/day ({\textpm} 0.013), respectively. When compared to a non-supplemented control (T1), offering T2 and T3 supplements increased MS production from 0.91 to 1.14 and 1.13kg MS/cow/day (P<0.01), respectively. The milksolids responses to T2 was 150g MS/cow/day greater in summer and winter than in spring and autumn (P<0.05). Stage of lactation, or form of supplement, had no effect on milksolids response (P>0.05). These results suggest that the milksolids response to supplementary feeding was determined by the extent supplementary feeding increased total ME intake. },
	issn = {1176-5283},
	author = {Penno JW and Holmes CW and MacDonald KA and Walsh BJ}
}
@conference {41009,
	title = {Management decision rules to optimise milksolids production on dairy farms},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {132-135},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {A review of grazing management research has provided a series of decision rules for the management of seasonal calving pastoral dairy farm systems. These rules have been used at the DRC No. 2 Dairy to remove subjectivity from the management of farm systems research. Cows are dried off with sufficient time for second calvers and mixed age cows to achieve condition scores of 5 and 4.5 by 1 June. Target pasture average herbage mass at calving is 2200 kg DM/ha. Optimum grazing management during autumn/winter, spring and summer has been shown to increase milksolids production by 29, 70 and 41 kg MS/ha, respectively. Grazing management during late spring must meet the dual objectives of generously feeding the herd, while maintaining pasture quality. Conserved pasture supplements should be fed in late autumn/early winter to meet cow condition, grazing management, and herbage mass objectives. Substantial increases in animal productivity can be achieved by sound farm management during periods of feed deficit. },
	issn = {1176-5283},
	author = {MacDonald KA and Penno JW}
}
@conference {41005,
	title = {Using nitrogen fertiliser to increase dairy farm profitability},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {117-120},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Five farmlets were established to investigate the profitability of using nitrogen fertiliser (N) to increase pasture supply and milksolids production. Farmlets were stocked with 3.34 (low) or 4.42 (high) Friesian cows/ha and received 0, 200 or 400 kg N/ha/year. Total annual pasture production was increased by 1.76 and 0.97 t DM/ha when 200 kg N/ha was applied and by 3.2 and 3.6 t DM/ha using 400 kg N/ha at the low and high stocking rate, respectively. Annual milksolids production increased by 142 and 218 kg MS/ha after the application of 200 and 400 kg N/ha, respectively. Increasing stocking rate from 3.34 to 4.42 cows/ha reduced milksolids production by 99 kg MS/cow. Applying 200 kg N/ha at the lower stocking rate increased economic farm surplus by $148/ha. Increasing stocking rate reduced total milksolids production and profitability at both rates of N. },
	issn = {1176-5283},
	author = {McGrath JM and Penno JW and MacDonald KA and Carter WA}
}
@conference {40919,
	title = {The effect of level of feeding during rearing on the first lactation milk yield of Friesian replacement heifers.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {57},
	year = {1997},
	month = {Jan},
	pages = {176-178},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Six nutritional regimes were imposed on Friesian heifers (n=270) from weaning to 22 months of age to determine the effect of level of feeding during rearing on subsequent milk production. Nutritional treatments resulted in groups weighing 480, 406, 455, 376, 398, and 342 kg (P<0.05) at 22 months of age. However, once the heifers entered the herd differences liveweight were lost. By 28 months of age the difference between the heaviest and lightest treatment groups was only 44 kg (P<0.05). Level of feeding from 90 to 200 kg liveweight had no effect on subsequent milkfat or protein yield (P>0.05). Heifers offered a high feeding level after 200 kg produced 9.6 kg more milkfat (P<0.01) and 6.6 kg more protein (P<0.01) than heifers offered the low feeding regime. These data suggest that Friesian heifers produce an additional 0.12 kg MS over their first lactation for each additional 1 kg liveweight gained during rearing. },
	issn = {1176-5283},
	author = {Penno JW and MacDonald KA and Bryant AM}
}
@conference {40920,
	title = {Growth of friesian calves offered three allowances of milk replacer.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {57},
	year = {1997},
	month = {Jan},
	pages = {179-181},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Milk and milk products are a more expensive source of dietary nutrients than pasture and cereal based supplements. Therefore restricting milk intake could reduce the cost of rearing replacement cattle. Friesian calves (n=60) were allocated to three balanced treatment groups receiving a High (29.8 kg), Medium (21.8 kg) or Low (16.6 kg) allowance of milk replacer (MR). Calves offered the Low allowance were weaned from MR at day 42, while the other two groups were weaned from MR at day 49 of the trial. Calves were weighed at days 0, 49, 70 and 119 following a 12 hour fast. The liveweight gain of the High group was greater (P<0.05) during days 0-49 and 49-119 than the Medium and Low groups. The calves on the Medium and Low MR allowance were 3 kg lighter on day 49 and 7 kg lighter on day 119 than those of the High MR allowance. Differences in growth rates between treatment groups prior to day 49 were smaller than would be expected from the large difference in metabolisable energy intake from MR. Furthermore, reducing MR allowance did not increase meal intake as was expected. It is likely that the calves partially compensated for a lower MR intake by increasing pasture dry matter intake. When choosing to restrict the level of nutrition offered to the young calf, the effect on animal performance both before and after weaning must be recognised. },
	issn = {1176-5283},
	author = {MacDonald KA and Penno JW}
}
@conference {40832,
	title = {Effect of body covers on the liveweight gain of heifer replacement calves and yearlings, and the liveweight gain and milksolids production of dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {56},
	year = {1996},
	month = {Jan},
	pages = {266-269},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Body covers are used on dairy stock in an attempt to increase  production by reducing the amount of energy required for thermoregulation.  Experiments were undertaken to determine the production response to  covering calves, yearlings and cows at several sites representing different  climatic conditions of the dairying districts of New Zealand. Calves (n=435) were randomly allocated to covered or uncovered treatments  on 5 farms in 1993 (n=249) using PVC covers and 4 farms in 1994 (n=186)  using Jute covers. Calves were covered for approximately 6 weeks prior to  weaning. The difference in total liveweight gain between the covered and  uncovered calves within farms ranged from +2.6 kg (},
	issn = {1176-5283},
	author = {MacDonald KA and Penno JW}
}
@conference {40826,
	title = {Effect of feeding turnips to dairy cows grazing limited amounts of pasture in mid to late lactation on milksolids production},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {56},
	year = {1996},
	month = {Jan},
	pages = {242-244},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Three groups of 20 cows were allocated to one of three feeding  treatments. A control group was offered only a restricted pasture allowance.  Treatments groups were offered pasture and turnips at either 4 or 8 kg  DM/cow/day. Cows offered 4 kg DM/cow and 8 kg DM/cow of turnips  produced 265 g MS/c/day (},
	issn = {1176-5283},
	author = {Penno JW and Bryant AM and Napper AR and Copeman PJA}
}
@conference {40824,
	title = {Effect of nitrogen fertiliser and supplements on pasture production and milksolids yield from dairy farm systems},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {56},
	year = {1996},
	month = {Jan},
	pages = {236-238},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Seven farmlets of 6.48 ha grazed by Friesian cows at stocking rates of  either 3.24 or 4.48 cows/ha were used to evaluate the effect of high rates of  nitrogen fertiliser (N) and rolled maize grain on milksolids (MS) production.  Annual applications of 213 and 379 kg N/ha increased annual net herbage  accumulation by 3350 and 4650 kg DM/ha respectively. At 3.24 cows/ha  extra DM resulted in a three fold increase in pasture conservation, providing  silage for use in late lactation, and increasing production by 72 kg MS/cow.  The extra pasture reduced the amount of supplement required at 4.48  cows/ha. Offering supplementary feed when cows were over grazing or  being under fed resulted in an extra 43g milkfat and 47g milk protein/kg  DM at the low stocking rate and 45g milkfat and 36g milk protein/kg DM at  the high stocking rate. Responses to extra feed were greatest when used to  extend lactation. Increased stocking rates will be necessary to maintain  pasture utilisation when large amounts of extra feed are introduced. },
	issn = {1176-5283},
	author = {Penno JW and Bryant AM and MacDonald KA}
}
@conference {40828,
	title = {Evaluation of the Cornell Net Carbohydrate and Protein System for dairy cows fed pasture-based diets},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {56},
	year = {1996},
	month = {Jan},
	pages = {251-254},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {This study evaluated the Cornell Net Carbohydrate and Protein System  (CNCPS) for dairy cattle consuming pasture-based diets. Data was obtained  from four grazing, and four indoor pasture feeding experiments (23 dietary  treatments) with dairy cattle in New Zealand and the United States. ME  requirements for maintenance were adjusted to account for grazing activity.  The model gave a reasonably good prediction of changes in condition score  (R2=0.79, slope not significantly different from 1), energy balance  (R2=0.76, slope not significantly different from 1), blood urea nitrogen  (BUN) (R2=0.91, underprediction bias of 0.4\%), microbial nitrogen flow  (R2=0.83, slope not significantly different from 1), and milk production.  The model underpredicted DM intake (R2=0.80, 11\% bias), and  overpredicted ruminal pH (R2=0.47, 1.8\% bias). These results indicate that  the CNCPS can be used to make realistic predictions of ruminal  fermentation and performance of dairy cows offered good quality pasture.},
	issn = {1176-5283},
	author = {Kolver ES and Barry MC and Penno JW and Muller LD}
}
@conference {40674,
	title = {Effect of level of nutrition on age of puberty and reproductive performance of Friesian heifers},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {55},
	year = {1995},
	month = {Jan},
	pages = {79-81},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Muscle proteolysis is controlled by a number of enzyme systems. The   reported effects of the calcium dependent proteinases (or calpains) on   myofibrillar structure have led to the speculation that this enzyme system  may   have an important role in regulating muscle growth and the post mortem   ageing process. Although at present there is no clear economic incentive,   meat quality has to be taken into account since the white meats of poultry   and pork are out competing the traditional red meats of lamb and beef.   Meat quality attributes may largely depend on slaughtering and post mortem   ageing regimes, however, variability also originates from the biological   characteristics of muscles which are undoubtedly environmentally and   genetically controlled. The aim of the present experiment is to examine the   effect of genotype, nutrition and their interactions on the calpain system.    Progeny from 3 sire breeds (Texel, Fat Southdowns and Lean Southdowns)   were weaned in December and placed onto one of two growth paths until   May (high (H) or low (L) rate of gain), from May until July these groups   were further divided into groups HH, HL, LL and LH. Animals were   slaughtered at the Ruakura commercial slaughter facility, samples for calpain   analysis were taken from the distal portion of the longissimus dorsi of the   animal within 20 minutes of slaughter. The assays were performed as   outlined by Dobbie et al., (1995).    Calpain-I differed significantly (p<0.05) between genotype (Texel 0.57   SDFat 0.50 SD Lean 0.41 U/g (SED 0.060). Calpastatin was significantly   (P<0.05) affected by plane of nutrition immediately after weaning. (H:2.61   L:2.35 U/g SED 0.126).    The results taken together suggest that complex physiological interactions   exist between genotype and nutrition with respect to the calpain system.   },
	issn = {1176-5283},
	author = {Penno JW and Macmillan KL and Bryant AM}
}
@conference {40669,
	title = {Effect of nitrogen fertiliser and summer rotation length on milk production in a dry Waikato summer.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {55},
	year = {1995},
	month = {Jan},
	pages = {64-66},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Muscling is considered important by the New Zealand meat industry.   As Texel cross lambs contain more muscle than most other sheep genotypes,   a muscling trial was undertaken using Texel and Oxford cross and High   Romney mixed sex lambs. Eighteen lambs were slaughtered from each   breed. The muscle, bone, subcutaneous and intermuscular fat were separated   from the leg and shoulder of the 54 right sides. The leg comprised on   average 64.4\% lean in the High Romneys, 66.2\% in the Oxford cross lambs   and 67.4\% in the Texel cross lambs (p<0.05). The corresponding figure for   shoulder lean 58.8\% (Romney), 59.9\% (Oxford) and 62.1 (Texel) (p<0.05).   The eye muscle area (cm2) for these lambs was 9.8 (Romney), 11.0 (Oxford)   and 11.7 (Texel). The muscle:bone ratio (weights) for 4 leg muscles to the   femur were 7.0 for the Romneys, 7.6 for the Oxford and 8.3 for the Texel   cross lambs (p<0.10). Only 2 non Texel lambs were classed E under the   European classification system.   },
	issn = {1176-5283},
	author = {Penno JW and Bryant AM and Carter WA and MacDonald KA}
}
@conference {40449,
	title = {A comparison of the effect of split and single applications of nitrogen fertiliser on dairy production},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {53},
	year = {1993},
	month = {Jan},
	pages = {33-36},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {The objectives of this study were to measure within day variation and day-to-day variation in selected metabolites in serum and milk samples obtained from animals in a herd of 20 Holstein-Friesian cows which grazed ryegrass/white clover pastures during peak lactation in October. In the first trial, the 20 cows were milk and blood sampled at 0630 h, 1030 h and 1430 h on 3 October and at 0630 h on the following day. Average metabolite concentrations in serum were within the ranges indicated by a regional laboratory as being normal for healthy cattle, but significant differences were associated with sampling time and among individual animals within this range. Blood and milk urea nitrogen (BUN and MUN) and blood beta hydroxybutyrate (BOH) concentrations increased by 1.82 },
	issn = {1176-5283},
	author = {Penno JW}
}
