New Zealand Strain Research Articles

Relationship between strains of Holstein cows, feeding strategies and udder health

Factores relacionados con el animal y el ambiente pueden afectar la frecuencia de mastitis, siendo la genética y la estrategia de alimentación algunos de dichos factores. El objetivo de este estudio fue analizar la frecuencia de mastitis clínica y los recuentos de células somáticas (RCS) de vacas Holando de dos biotipos, Norteamericano (NA) y Neozelandés (NZ), bajo dos estrategias de alimentación (pastura o mixto). En la Unidad Experimental de Lechería de INIA La Estanzuela (Colonia, Uruguay) fueron agrupadas 120 vacas en 4 tratamientos según la combinación de biotipo y estrategia de alimentación (n=30). La cantidad de vacas con mastitis clínica y los RCS fueron registrados mensualmente durante una lactación. Hubo una interacción entre el biotipo y la paridad de las vacas (primíparas y multíparas) (P=0,04) para la frecuencia de mastitis. Vacas primíparas NA presentaron menor probabilidad de presentar mastitis clínica (ODR: 0,003). Por el contrario, las vacas multíparas NA fueron las que presentaron mayor probabilidad de experimentar mastitis clínica (ODR: 0,12), mientras que las vacas de origen NZ mostraron valores intermedios (ODR primíparas: 0,082; ODR multíparas: 0,066). La estrategia de alimentación no afectó la frecuencia de mastitis ni los RCS. Tampoco el biotipo afectó el RCS. En conclusión, sin importar la estrategia de alimentación, la frecuencia de mastitis clínica fue diferente según el biotipo, pero estas diferencias fueron influenciadas por el número de partos de los animales. Los RCS no fueron afectados por la estrategia de alimentación o el biotipo animal.

Yersiniosis in New Zealand.

The rate of yersiniosis in New Zealand (NZ) is high compared with other developed countries, and rates have been increasing over recent years. Typically, >99% of human cases in NZ are attributed to Yersinia enterocolitica (YE), although in 2014, a large outbreak of 220 cases was caused by Yersinia pseudotuberculosis. Up until 2012, the most common NZ strain was YE biotype 4. The emergent strain since this time is YE biotype 2/3 serotype O:9. The pathogenic potential of some YE biotypes remains unclear. Most human cases of yersiniosis are considered sporadic without an identifiable source. Key restrictions in previous investigations included insufficient sensitivity for the isolation of Yersinia spp. from foods, although foodborne transmission is the most likely route of infection. In NZ, YE has been isolated from a variety of sick and healthy domestic and farm animals but the pathways from zoonotic reservoir to human remain unproven. Whole-genome sequencing provides unprecedented discriminatory power for typing Yersinia and is now being applied to NZ epidemiological investigations. A “One-Health” approach is necessary to elucidate the routes of transmission of Yersinia and consequently inform targeted interventions for the prevention and management of yersiniosis in NZ

Whole-genome sequencing from the New Zealand Saccharomyces cerevisiae population reveals the genomic impacts of novel microbial range expansion.

Saccharomyces cerevisiae is extensively utilized for commercial fermentation, and is also an important biological model; however, its ecology has only recently begun to be understood. Through the use of whole-genome sequencing, the species has been characterized into a number of distinct subpopulations, defined by geographical ranges and industrial uses. Here, the whole-genome sequences of 104 New Zealand (NZ) S. cerevisiae strains, including 52 novel genomes, are analyzed alongside 450 published sequences derived from various global locations. The impact of S. cerevisiae novel range expansion into NZ was investigated and these analyses reveal the positioning of NZ strains as a subgroup to the predominantly European/wine clade. A number of genomic differences with the European group correlate with range expansion into NZ, including 18 highly enriched single-nucleotide polymorphism (SNPs) and novel Ty1/2 insertions. While it is not possible to categorically determine if any genetic differences are due to stochastic process or the operations of natural selection, we suggest that the observation of NZ-specific copy number increases of four sugar transporter genes in the HXT family may reasonably represent an adaptation in the NZ S. cerevisiae subpopulation, and this correlates with the observations of copy number changes during adaptation in small-scale experimental evolution studies.

The effect of stocking rate and calving date on reproductive performance, body state, and metabolic and health parameters of Holstein-Friesian dairy cows

Two groups of Holstein-Friesian dairy cows with different mean calving dates (CD) were established from within the existing research herd at Moorepark (Teagasc, Ireland). Animals were assigned to either an early calving (mean CD February 12) treatment or a late calving (mean CD February 25) treatment. Animals within each CD treatment were randomly allocated to 1 of 3 stocking rate (SR) treatments, low (2.51 cows/ha), medium (2.92 cows/ha), or high (3.28 cows/ha), which were designed to represent 3 alternative whole-farm SR in a spring-calving, grass-based milk production system following abolition of the European Union milk quotas. A total of 138 spring-calving dairy cows, comprising 2 strains of Holstein-Friesian, North American (NA) and New Zealand (NZ), were used in each year (2009 and 2010). The effects of CD, SR treatment, genetic strain, and their interactions on reproductive performance, body weight, body condition score, blood metabolites, hormone and immunological parameters, and health status were analyzed. Stocking rate and CD had no effect on pregnancy rates, immunological parameters, or health status, although a tendency was observed for more reproductive intervention as SR increased. Earlier calving and increased SR also resulted in reduced body weight, body condition score, and metabolic status in early lactation. Strain of Holstein-Friesian also affected reproductive performance. The NZ strain tended to have a higher submission rate and 42 d pregnancy rate compared with the NA strain, and a strain by SR interaction was observed for pregnancy rate to first service. Earlier calving and increased SR can be achieved without adverse effects on overall pregnancy rates. The existence of a SR by strain interaction for several reproductive variables suggests that the smaller NZ strain is better adapted to increased SR systems.

The influence of strain of Holstein-Friesian cow and feeding system on greenhouse gas emissions from pastoral dairy farms

The purpose of this study was to model the effect of 3 divergent strains of Holstein-Friesian cows in 3 pasture-based feed systems on greenhouse gas (GHG) emissions. The 3 strains of Holstein-Friesian compared were high-production North American (HP), high-durability North American (HD), and New Zealand (NZ). The 3 feed systems were a high grass allowance system (MP, control); high stocking rate system (HS); and high concentrate supplementation system (HC). The MP system had an overall stocking rate of 2.47 cows/ha and received 325kg of dry matter concentrate per cow in early lactation. The HS system had a similar concentrate input to the MP system, but had an overall stocking rate of 2.74 cows/ha. The HC system had a similar overall stocking rate to the MP system, but 1,445kg of dry matter concentrate was offered per cow. A newly developed integrated economic-GHG farm model was used to evaluate the 9 milk production systems. The GHG model estimates on-farm (emissions arising within the farm's physical boundaries) and production system (incorporating all emissions associated with the production system up to the point milk leaves the farm gate) GHG emissions. Production system GHG emissions were always greater than on-farm emissions, and the ranking of the 9 systems was usually consistent under both methods. The exception was the NZ strain that achieved their lowest GHG emission per unit of product in the HC system when indirect emissions were excluded, but their lowest emission was in the HS system when indirect emissions were included. Generally, the results showed that as cow strain changed from lower (HD and NZ) to higher genetic potential (HP) for milk production, the GHG emission per kilogram of milk solids increased. This was because of a decline in cow fertility in the HP strain that resulted in a higher number of nonproductive animals, leading to a lower total farm milk solids production and an increase in emissions from nonproductive animals. The GHG emission per hectare increased for all strains moving from MP to HS to HC feed systems and this was associated with increases in herd total feed intake. The most profitable combination was the NZ strain in the HS system and this combination resulted in a 12% reduction in production system GHG emission per hectare compared with the NZ strain in the HC system, which produced the highest emissions. This demonstrates that grass-based systems can achieve high profitability and decreased GHG emissions simultaneously.

Responses of North American and New Zealand strains of Holstein–Friesian dairy cattle to homeostatic challenges during early and mid-lactation

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

Evaluation of Ayurvedic plants for anti-atherosclerotic and anti-hyperlipidemic effects

AIM: To study effects of Ayurvedic plants, Plumbago zeylanicus (Pz), Phyllanthus emblica (Pe), Cyperus rotundus (Cr) and Embelia ribes (Er) on prevention of atherosclerosis and hyperlipidemia. Methodology: The study was carried out in two parts after Animal Ethics Committee approval. In both the parts, animals were assigned to groups viz. Normal control, Disease control, Atorvastatin (AT), Pe, Pz, Cr and Er. Standardized aqueous extracts of test drugs in doses equivalent to human therapeutic dose were administered orally. In Part 1, male adult New-Zealand strain rabbits were administered high cholesterol diet pellets along with test drugs/vehicle for 45 days. On 46th day, lipid profile and histopathology of aorta were studied. In Part 2, male wistar rats (150–200 gm) received test drug/vehicle with cholesterol supplementation (CS: 400mg/kg with choline in coconut oil p.o.) for 35 days. Lipid profile and liver HMG-CoA reductase activity and aortic MDA were estimated on 36th day. Data was analysed using ANOVA followed by post hoc tests. Results: In part 1, only AT and Pe prevented hyperlipidemia induced by HCD. However, all the test drugs exhibited anti-atherosclerotic potential as seen from significant reduction in mean plaque area and percent luminal encroachment by the plaques. The best results were observed with AT and Pz, followed by Cr. In Part 2, AT prevented hyperlipidemia and increased HDL-C (p<0.01). Of the test drugs, Pz reduced triglycerides and VLDL-C (p<0.05) and increased HDL-C (p<0.05). Pe reduced LDL-C (p<0.01) and showed trend to reduce total cholesterol. AT, Pz and Pe also decreased HMG-CoA reductase activity and prevented rise in vascular MDA in response to CS. Conclusion:Pz showed the best anti-atherosclerotic effect comparable to AT. Anti-hyperlipidemic effects of Pz and Pe appear to be responsible for the anti-atherosclerotic activity. The mechanisms responsible for anti-atherosclerotic potential of Cr and Er need to be explored. Acknowledgement: 1. Dept. of AYUSH Govt. of India 2. Zandu Pharmaceuticals Works Ltd.

A Comparison of Three Strains of Holstein-Friesian Grazed on Pasture and Managed Under Different Feed Allowances

This experiment compared Holstein-Friesian (HF) cows of New Zealand (NZ) origin representative of genetics present in the 1970s (NZ70; n=45) and 1990s (NZ90; n=60), and a group of HF cows of North American origin with 1990s genetics (NA90; n=60), which were managed in grazing systems with a range of feeding allowances (4.5 to 7.0 t/cow per yr) over 3 yr. The NZ70 cows had the lowest Breeding Worth genetic index and the lowest breeding values for yields of fat, protein, and milk volume; the NZ90 and NA90 cows were selected to have similar breeding values for milk traits and were representative of cows of high genetic merit in the 1990s. The NZ90 cows had a higher milk protein concentration (3.71%) than either the NA90 (3.43%) or the NZ70 cows (3.41%), and a higher milk fat concentration (4.86%) than the NA90 cows (4.26%) with a level similar to the NZ70 cows (4.65%). The NZ90 cows produced significantly greater yields of fat, protein, and lactose than the NA90 and NZ70 cows. The NZ70 cows had the lowest mean annual body weight (473kg) but the highest body condition score (BCS; 5.06). Days in milk were the same for the 2 NZ strains (286 d in milk), both of which were greater than the NA90 cows (252 d in milk). There was no genotype × environment interaction for combined milk fat and protein yield (milksolids), with NZ90 producing 52 kg/cow more than the NA90 at all feeding levels. The NZ70 strain had the highest seasonal average BCS (5.06), followed by the NZ90 (4.51) and the NA90 (4.13) strains on a 1 to 10 scale. Body condition score increased with higher feeding levels in the 2 NZ strains, but not in the NA strain. The first-parity cows commenced luteal activity 11 d later than older cows (parities 2 and 3), and the NA90 cows commenced luteal activity 4 and 10 d earlier than the NZ70 and NZ90 cows. Earlier estrus activity did not result in a higher in-calf rate. The NZ70 and NZ90 cows had similar in-calf rates (pregnancy diagnosed to 6 wk; 69%), which were higher than those achieved by NA90 cows (54%). Results showed that the NA90 strain used in this experiment was not suitable for traditional NZ grazing systems. Grazing systems need to be modified if the NA90 strain is to be successfully farmed in NZ. The data reported here show that the NA90 cows require large amounts of feed, but this will not prevent them from having a lower BCS than the NZ strains. Combined with poor reproductive performance, this means that NA90 cows are less productive than NZ HF in pasture-based seasonal calving systems with low levels of supplementation.

A Comparison of Three Strains of Holstein-Friesian Cows Grazed on Pasture: Growth, Development, and Puberty

With the introduction of a protein milk payment system in New Zealand in 1988, there was an influx of North American (NA) Holstein-Friesian (HF) genetics into New Zealand (NZ) dairy herds, leading to an increase in the average percentage of NA genetics in NZ HF cows—from 2% in 1980 to 38% in 1999. Of interest has been the effect this change has had on farm profitability and on the management required for these animals, as well as the phenotypic changes that have occurred within the national herd under the breeding programs operated in NZ from 1970 to 1990. The objective of this study was to quantify differences in body dimensions, body weights, and puberty-related parameters among 3 strains of HF, representing animals of NZ origin representative of the genetics present in 1970 and 1990 and of NA origin with 1990s genetics. A total of 172 animals born in 1999 were compared. The strains were 1) NZ70, a strain of NZ Friesian (average 7% NA genetics) equivalent to high-genetic-merit (high Breeding Worth) cows farmed in the 1970s; 2) NZ90, a strain of HF of NZ origin (average 24% NA genetics) typical of the animals present in the 1990s; and 3) NA90, a strain of HF of NA origin (average of 91% NA genetics) typical of animals present in the 1990s. The differences in BW among all strains were significant at 6 and 12 mo of age. At 15 and 24 mo, the 2 NZ strains were significantly lighter than the NA90 animals. At 24 mo of age (i.e., prior to first calving), the NA90 strain animals (BW=515kg) were 22 and 34kg heavier than the NZ90 and NZ70 strains. The body length of the NA90 strain was greater than either of the 2 NZ strains; the differences among the NA90 strain and the 2 NZ strains varied from 2 to 6cm, with the differences generally being greater at older ages. The trend in heart girth difference among strains was similar to that observed for body length. The wither height of the NA90 animals was greater than that of the NZ strains by 1 to 7cm, although there was no significant difference between the NA90 and NZ90 strains at birth. At puberty the NA90 heifers were 20 d older and 20kg heavier than the NZ90 heifers, which in turn were 25kg and 25 d older than the NZ70 heifers. The NA90 strain had a heavier mature body weight, and their older age at puberty suggested either that they mature later or that, under pastoral conditions, their growth rate is limited by their inability to consume sufficient metabolizable energy as grazed pasture, with a consequent delay in puberty. Results from this study will be useful in revising target BW in growing heifers of different germplasm.

Influence of Holstein-Friesian Strain and Feed System on Body Weight and Body Condition Score Lactation Profiles

The objective of the present study was to determine effects of strain of Holstein-Friesian and feed system on body weight (BW) and body condition score (BCS; scale of 1 to 5) lactation profiles in seasonal-calving, grass-based milk production systems. The 3 strains of Holstein-Friesian compared differed in milk production potential and were high-production North American (HP), high-durability North American (HD), and New Zealand (NZ). The 3 feed systems compared were a high grass allowance feed system typical of spring-calving herds in Ireland (MP); an increased stocking rate system (HS); and an increased concentrate supplementation system (HC), each maintained within a separate farmlet. The data comprised 20,611 weekly BW and 7,920 BCS records assessed every 3 wk across 5 yr on 584 lactations. An exponential function was used to model BW and BCS lactation profiles across feed systems. Across feed systems, the NZ strain was significantly lighter (545kg) but had greater average BCS (3.10 units) compared with the HP (579.3kg and 2.76 units, respectively) and HD strains (583.2kg and 2.87 units, respectively). Across feeding systems, the HD and HP strains exhibited a greater loss of BCS in early lactation (0.27 and 0.29 units, respectively) compared with the NZ strain (0.21 units). The HP strain failed to gain BCS over the entire lactation. Concentrate input did not affect the rate of BCS or BW loss in early lactation or BCS at 60 DIM. This study extends previous research outlining the greater suitability of the NZ strain to the low-cost grass-based system of milk production predominantly operated in Ireland.

Effect of strain of Holstein–Friesian and feed system on calving performance, blood parameters and overall survival

The objective of the present study was to quantify the effect of strain of Holstein–Friesian and pasture-based feeding system on calving performance, blood parameters and overall survival within a seasonal calving milk production system. The three strains of Holstein–Friesian compared were high production North American (HP), selected entirely for milk production, high durability North American (HD), selected based on milk production, fertility and muscularity traits, and New Zealand (NZ) selected from a seasonal calving pasture-based system. The three feed systems compared were a high grass allowance feed system typical of spring calving herds in Ireland (MP; control); an increased stocking rate system (HS) and an increased concentrate supplementation system (HC). Data comprised up to 585 lactations on 240 cows. Data were analysed using linear mixed models, generalised estimating equations and survival analysis. Strain of Holstein–Friesian had no significant effect on calving difficulty or rate of stillbirths while the effect of feed system on calving difficulty and rate of stillbirths approached significance. Strain of Holstein–Friesian had no significant effect on plasma metabolite or hormone concentrations around parturition, with the exception of urea concentration. At the beginning of the breeding season the NZ strain had lower plasma concentrations of NEFA (0.20 mmol/l) and higher IGF-I (86.8 ng/ml) than the HD (0.24 mmol/l and 66.9 ng/ml, respectively) and HP (0.26 mmol/l and 64.0 ng/ml, respectively) strains. The higher IGF-I concentration of the NZ strain was maintained during the breeding season. The NZ and HD strains survived longer than the HP strain with median survival days post-first calving of 1372, 1367 and 1033 respectively, while feed system had no significant effect on overall survival rate over the study period.

Economic Comparison of Divergent Strains of Holstein-Friesian Cows in Various Pasture-Based Production Systems

The objective of this paper was to compare the economic efficiency of 3 divergent strains of Holstein-Friesian cows—high-production North American (HP), high-durability North American (HD), and New Zealand (NZ)—across a variety of Irish pasture-based production systems: Moorepark (MP), high concentrate (HC), and high stocking rate (HS). Physical performance data were obtained from a 5-yr study conducted previously. The economic performance of each strain and feed system was derived for 3 production scenarios: European Union (EU) milk quota applied at the farm level using predicted future prices and costs (S1); EU milk quota applied at the industry level, thus permitting quota leasing at predicted future prices and costs (S2); and EU milk quota applied at the industry level with a limitation on land availability (S3). The economic results showed that in a fixed milk quota scenario, the NZ strain in the MP and HS feed systems returned the highest profitability. The HD strain in the MP and HS feed systems proved the next most profitable, whereas the HP animals were least profitable in all feed systems. Similar to S1, in S2 the NZ were most profitable; however, the difference between the MP and HS was much smaller. The HP strain proved least profitable in all feed systems. In S3, the NZ strain was again most profitable; however, within that scenario the HS feed system was optimal. These results show that exclusive genetic selection for increased milk production results in reduced farm profitability because the productivity gains achieved are outweighed by associated increases in reproductive wastage costs in a pasture-based system. These results reinforce the economic value of genetic improvement based on a selection index encompassing traits of economic significance pertinent to the production environment.

The influence of strain of Holstein‐Friesian dairy cow and pasture‐based feeding system on grazing behaviour, intake and milk production

AbstractA comparative study of grazing behaviour, herbage intake and milk production of three strains of Holstein‐Friesian dairy cow was conducted using three grass‐based feeding systems over two years. The three strains of Holstein‐Friesian cows were: high production North American (HP), high durability North American (HD) and New Zealand (NZ). The three grass‐based feeding systems were: high grass allowance (MP), high concentrate (HC) and high stocking rate (HS). In each year seventy‐two pluriparous cows, divided equally between strains of Holstein‐Friesian and feeding systems were used. Strain of Holstein‐Friesian cow and feeding system had significant effects on grazing behaviour, dry matter (DM) intake and milk production. The NZ strain had the longest grazing time while the HD strain had the shortest. The grazing time of cows in the HC system was shorter than those in both the HS and MP systems. There was a significant strain of Holstein‐Friesian cow by feeding system interaction for DM intake of grass herbage and milk production. The NZ strain had the highest substitution rate with the HP strain having the lowest. Hence, response in milk production to concentrate was much greater with the HP than the NZ strain. Reduction in milk yield as a consequence of a higher stocking rate (MP vs. HS system) was, however, greater for the HP and HD strains compared with the NZ strain. The results suggest that differences in grazing behaviour are important in influencing DM intake and milk production.

Effect of strain of Holstein–Friesian and feed system on udder health and milking characteristics

Abstract The objective of this study was to quantify the effect of three alternative strains of Holstein–Friesian dairy cows, parity and feed system on udder health and milk flow characteristics. The three strains of Holstein–Friesian compared were, high production North American (HP), high durability North American (HD) and New Zealand (NZ). The three feed systems compared were, a high grass allowance feed system typical of spring calving herds in Ireland (MP), a higher concentrate system (HC), and a higher stocking rate system (HS). The data comprised up to 584 lactations from 240 cows across 5 years, from one research herd. The NZ stain had significantly higher average lactation somatic cell count (87,553 cells/ml) than the HP (60,475 cells/ml) or HD strains (59,278 cells/ml). Nonetheless, differences between strains were not biologically important. No significant strain effect on incidence of clinical mastitis was observed; average lactation incidence of clinical mastitis was 26%. The NZ strain had the highest peak milk flow (5.45 kg/min) and the shortest average milking duration (6.60 log sec/day). Feed system had no significant effect on udder health while significant feed system effects were observed on milking characteristics including average milk flow and average and maximum milking duration. This study indicates significant variation in somatic cell count and milking characteristics between strains, which when coupled with their economic importance, suggest the necessity to include these in overall breeding objectives.

The effect of strain of Holstein-Friesian dairy cow and pasture-based system on grass intake and milk production

AbstractThe objective of this study was to investigate the effects of strain of Holstein-Friesian cow, pasture-based feeding system (FS) and their interaction on milk production, dry matter (DM) intake and energy balance over 3 years consecutively. The three strains were: high milk production North American (HP), high fertility and survival (durability) North American (HD) and New Zealand (NZ). The FS were: a high grass allowance (HG FS), a high concentrate (HC FS) and a high stocking rate (HS FS). A separate farmlet existed for each FS and a total of 99, 117 and 117 animals were used in year 1, year 2 and year 3, respectively, divided equally between strains and FS. Individual animal intakes were estimated three times each year at pasture; in May (P1), in July (P2) and October (P3), corresponding on average to day 102, 177 and 240 of lactation, respectively. The HP cows achieved the highest milk yield, the NZ the lowest, while the HD was intermediate; the HP achieved the highest solid corrected milk yield with no difference between the NZ and HD strains. The grass DM intake of the HP strain was highest ( P&lt;0·001) in all feeding systems. There was a significant strain×FS interaction for yield of milk, fat and protein, grass DM and total DM intake. The milk production response to the HC FS in P1 and P2 was significantly greater for both the HP and HD strains than for the NZ strain, while in P3 the response was highest for the HP, lowest for the NZ and intermediate for the HD. The reduction in pasture DM intake per kg of concentrate was greatest for the NZ strain, lowest for the HP and intermediate for the HD strain. The NZ strain also had the highest grass DM intake per kg live weight. The existence of strain×FS interactions for production and DM intake indicate that greater knowledge of both genotype and feeding environment is required to predict animal performance.

The effect of strain of Holstein–Friesian, feeding system and parity on lactation curves characteristics of spring-calving dairy cows

The purpose of the present study was to investigate the influence of strain of Holstein–Friesian (HF) cow and feeding system (FS) on the lactation curve characteristics of spring-calving cows. The Wilmink model was used to analyse the lactation curves. The three strains of HF cows compared were high production North American (HP), high durability North American (HD) and high Breeding Worth New Zealand (NZ). The three FS compared were a high milk output from pasture feed system (MP), a high concentrate feed system (HC) and a high stocking rate feed system (HS). A repeated measures model with a factorial arrangement of treatments was used to determine the influence of strain of HF, FS, parity and their interactions on the shape of the lactation curve. The curve was described based on yield at calving, the degree of ascendancy between calving and peak yield, and the persistency after peak yield. Analysis of the residuals indicated a good fit of the Wilmink curve to the data set. Strain of HF, FS, parity and the interaction of strain of HF with FS had significant effects on lactation curve characteristics. In all three FS, the HP strain achieved the highest milk production post-claving and peak yield, with the lowest persistency of lactation. In the HC system, milk production post-claving and at peak yield were higher for all three strains. Offering higher levels of concentrate supplementation to the HP strain on a pasture-based system improved their persistency of lactation. The highest persistency of lactation was achieved with NZ strain. The highest milk production post-claving and at peak and lowest persistency was achieved with third parity cows. The existence of strain by feed system interactions for lactation curve parameters clearly exhibits that the optimum system of production varies with strain of HF.

The effect of strain of Holstein-Friesian cow and feeding system on reproductive performance in seasonal-calving milk production systems

AbstractThree strains of Holstein-Friesian (HF) cows: high production North American (HP), high durability North American (HD) and New Zealand (NZ) were assigned, within strain, to one of three pasture-based feeding systems: Moorepark (MP), high concentrate (HC), and high stocking rate (HS). The effects of strain of HF, feeding system and parity on milk production, body condition score (BCS), live weight, energy balance and reproductive performance were studied using a repeated measures model with a factorial arrangement of strain ofHF and feeding systems. Associations between these variables and conception to first service (CONCEPT1), conception to first and second service (CONCEPTl_2), pregnancy rate at 6 weeks (PREG6) and overall pregnancy rate (PREG) were assessed using logistic regressions. When treatment means were compared, the NZ strain had a shorter gestation length and a higher CONCEPT1J2 than both the HP and HD strains. Similarly, the NZ strain had a higher PREG6 and PREG than the HP strain. Feeding system had no significant effect on reproductive performance. The HP strain had the highest milk yield at first AI and peak milk yield, the NZ strain had the lowest milk yield while the HD strain was intermediate. The energy balance of the NZ strain was higher than that of the HP and HD strains. The NZ strain had the lowest live weight and highest BCS; the HD strain had the highest live weight and the HP strain had the lowest BCS. The results show that dairy cows with superior genetic merit for fertility traits have better reproductive performance.

The effect of strain of Holstein-Friesian cow and feeding system on postpartum ovarian function, animal production and conception rate to first service

Three strains of Holstein-Friesian (HF): high production North American (HP), high durability North American (HD) and New Zealand (NZ) cows were assigned, within strain, to one of three pasture-based feeding systems: (1) the Moorepark (control) system (MP), (2) a high concentrate system (HC), (3) a high stocking rate system (HS). Ovarian function was assessed using milk progesterone samples, collected from 117 cows in each of two successive years, with 81 animals being common to both years. Milk samples were collected thrice weekly, beginning day 5 post-calving and continued to day 26 after first AI. Data from animals subsequent to reproductive hormonal treatment were removed from the analysis. Feed system and strain of HF by feeding system interaction had no significant effect on re-establishment of ovarian activity and subsequent conception rate to first AI. Strain of HF had no significant effect on interval to commencement of luteal activity (CLA). The mean interval to CLA was 32.9 days (S.E. 1.18), ranged from 6 to 100 days, with 42 and 85% of cows ovulating by day 26 and 60, respectively. The HD (62%) and NZ (57%) strains had a higher conception rate to first AI than the HP strain (40%), ( P < 0.05). Retrospective analysis categorised all cows into four quartiles based on interval to CLA (<20 days, 20–26 days, 27–44 days and >44 days). Cows in the first and fourth CLA quartiles had a longer calving to conception interval ( P < 0.05). Cows with abnormal progesterone profiles (38.4%) had an earlier mean calving date, with a similar submission rate and conception rate to first service compared to cows with normal hormonal profiles. There was no significant difference in luteal activity or reproduction performance, apart from calving to conception interval, between cows that conceived or did not conceive to first service. These results indicate that while conception rate to first service differed between strains of HF cow, this was not associated with differences in the onset and pattern of luteal activity post partum.

The effect of strain of Holstein-Friesian and feeding system on grazing behaviour, herbage intake and productivity in the first lactation

AbstractA comparative study of grazing behaviour, herbage intake and milk production was conducted using three strains of Holstein-Friesian (HF) heifer : 33 high production North American (HP), 33 high durability North American (HD) and 33 New Zealand (NZ) animals. Heifers were assigned, within strain, to one of three grass-based feeding systems : (1) the Moorepark (control) system (MP), (2) a high concentrate system (HC), (3) a high stocking rate system (HS). Strain of HF had no significant effect on grazing time or number of grazing bouts. The NZ strain had longer grazing bouts (P&lt; 0.01) and spent a lower proportion of time ruminating (P&lt; 0.05) than both the HP and HD strains. There was a significant strain ✕ feeding system interaction for biting rate. The biting rate of the NZ strain was reduced in the HC system. Biting rates in the HS feeding system were significantly higher (P&lt; 0.001) than in the MP system. Heifers on HC had shorter grazing time (P&lt; 0.01) with grazing bouts of shorter duration (P&lt; 0.01). Increasing stocking rate (HS) decreased the proportion of time ruminating (P&lt; 0.001) and tended to shorten grazing bouts (P = 0.06). The HP strain had higher (P&lt; 0.05) herbage and total dry matter (DM) intakes than the NZ strain, while the HD strain was intermediate. Concentrate supplementation reduced (P&lt; 0.001) herbage DM intake but increased (P&lt; 0.001) total DM intake. The reduction of herbage DM intake per kg of concentrate DM intake (substitution rate) was greater for the NZ than the HP strain. The HP produced significantly higher milk, fat, protein and lactose yields than the NZ, while the HD strain was intermediate. The milk fat content of the NZ was higher than both the HP and HD strains, while the protein content was higher than the HP strain. Concentrate supplementation (HC v . MP) significantly increased yields of milk and milk components. Milk production responses to the HC system were much greater with the HP than the NZ strain. Increasing stocking rate (MP v . HS) significantly decreased milk protein yield. The results indicate that the choice of strain of HF may depend on the feeding system.

Postpartum anovulatory intervals in two genotypes of pasture-fed Holstein-Friesian dairy cattle

In pasture-based dairying systems it is important to maintain a 365-day calving interval, which requires that cows have a rapid resumption of postpartum ovulatory activity and high conception rates. The major form of infertility in New Zealand (NZ) dairy cows is an extended postpartum anovulatory interval (ppai; Macmillan, 2002), a problem that can be exacerbated by low body condition score (BCS) at calving (McDougall, 1995). Furthermore, Holstein cows, originating from North American genetic strains (Overseas; OS), which have been widely used in NZ in recent years, have longer intervals to first mating and conceive later than do NZ strains, suggesting a possible delay in the initiation of postpartum cyclicity (Harris and Winkleman, 2000). Worldwide, there is concern over an apparent decline in the fertility of Holstein-Friesian dairy cattle (Butler et al., 1995; Royal et al., 2000). The purpose of this trial was to determine whether there was a difference in ppai and BCS between NZ and OS Holstein Friesians that may affect reproductive performance.