scholarly journals Effect of Sex of Birth and Stage of Lactation on Milk Production and Its Components in the Holstein-FriesianCows

2018 ◽  
Vol 8 (2) ◽  
pp. 88-91
Author(s):  
Raed Kawkab Al-Muhja
Keyword(s):  
Milk Production ◽  
Milk Fat ◽  
Significant Interaction ◽  
Chemical Components ◽  
College Of Agriculture ◽  
The Third ◽  
Stage Of Lactation ◽  
A Value ◽  
Holstein Friesian ◽  
Main Components

This study was conducted on data which  collected from the filed Cattle in the college  of Agriculture / University of Baghdad for the period from 1/7/2013 to 1/10/2013, which included 28 cows of Holstein Friesian to show the effect of sex of birth and the stage of lactation on Milk production  and  the main components. Our results showed The highest average milk production for female foster cows recorded in the first week with a value of 233L . The results show that had no significant effect  of sex of birth on milk production  and  the main components. The results  showed  that the highest values ​​of milk fat, lactose and minerals in the seventh week of lactation, which values ​​were (3.559, 4.337and 0.638%) respectively, while the highest protein value was recorded in the third week (2.821%). There was no significant interaction  among chemical components  and stage of lactation , despite the superiority of the milk of female foster cows on the milk of male foster cows in some traits

Effects of feeding peas to high-producing dairy cows

1995 ◽  
Vol 75 (4) ◽  
pp. 625-629 ◽  
Author(s):  
R. R. Corbett ◽  
L. A. Goonewardene ◽  
E. K. Okine
Keyword(s):  
Dairy Cows ◽  
Milk Production ◽  
Milk Yield ◽  
Milk Fat ◽  
Dairy Herd ◽  
Protein Source ◽  
Canola Meal ◽  
Stage Of Lactation ◽  
Nutrient Analyses ◽  
Protein Milk

The effect of substituting peas for soybean and canola meals as a protein source in a high-producing dairy herd was studied in 66 Holstein cows, divided into two groups based on stage of lactation, parity, level of milk production and days in milk. Two 18.5% crude protein grain concentrate diets were formulated based on the nutrient analyses of the forages available. The control grain mix contained standard protein sources, principally soybean and canola meal (SBM\CM) while the test grain mix was formulated to contain approximately 25% field peas as the major source of protein. Both grain rations were formulated to the same nutrient specifications and balanced for undegradable protein. The duration of the trial was 6 mo during which grain feeding levels were adjusted monthly based on milk yield. For cows in early lactation, 4% fat-corrected milk yield was higher (P < 0.05) for cows fed pea based concentrates (31.3 kg d−1) than for cows fed SBM\CM supplement (29.7 kg d−1). Fat-corrected milk yield was not affected by source of protein in mid- and late-lactation cows. Fat-corrected milk production was not different (P > 0.05) for cows fed SBM\CM compared with cows fed the pea supplement when cows across all stages of lactation were included in the analyses. Milk fat percent was significantly higher (P < 0.05) for early- and mid-lactation cows fed the pea supplement. The results suggest that peas can be substituted for SBM\CM as a protein source for high-producing dairy cows. Key words: Dairy cow, pea, soybean and canola meal supplement, undegradable protein, milk production

Replacing wheat with canola meal and maize grain in the diet of lactating dairy cows: Feed intake, milk production and cow condition responses

2017 ◽  
Vol 84 (3) ◽  
pp. 240-247 ◽  
Author(s):  
Ruairi P McDonnell ◽  
Martin vH Staines
Keyword(s):  
Dairy Cows ◽  
Milk Production ◽  
Milk Fat ◽  
Milk Protein ◽  
Daily Intake ◽  
Canola Meal ◽  
Grass Silage ◽  
Holstein Friesian ◽  
Maize Grain ◽  
The Difference

This research paper describes the effect of partially replacing wheat with maize grain and canola meal on milk production and body condition changes in early lactation Holstein-Friesian dairy cows consuming a grass silage-based diet over an 83-d period. Two groups of 39 cows were stratified for age, parity, historical milk yield and days in milk (DIM), and offered one of two treatment diets. The first treatment (CON) reflected a typical diet used by Western Australian dairy producers in summer and comprised (kg DM/cow per d); 8 kg of annual ryegrass silage, 6 kg of crushed wheat (provided once daily in a mixed ration), 3·6 kg of crushed lupins (provided in the milking parlour in two daily portions) and ad libitum lucerne haylage. The second treatment diet (COMP) was identical except the 6 kg of crushed wheat was replaced by 6 kg of a more complex concentrate mix (27% crushed wheat, 34% maize grain and 37% canola meal). Lucerne haylage was provided independently in the paddock to all cows, and no pasture was available throughout the experiment. The COMP group had a greater mean overall daily intake (22·5vs20·4 kg DM/cow) and a higher energy corrected milk (ECM) yield (29·2vs27·1 kg/cow;P= 0·047) than the CON cows. The difference in overall intake was caused by a higher daily intake of lucerne haylage in COMP cows (4·5vs2·3 kg DM/cow). The CON group had a higher concentration of milk fat (42·1vs39·3 g/kg;P= 0·029) than COMP cows. Milk protein yield was greater in COMP cows (P< 0·021); however, milk fat yield was unaffected by treatment. It is concluded that partially replacing wheat with canola meal and maize grain in a grass silage-based diet increases voluntary DMI of conserved forage and consequently yields of ECM and milk protein.

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

2004 ◽  
Vol 78 (1) ◽  
pp. 169-178 ◽  
Author(s):  
M. Linnane ◽  
B. Horan ◽  
J. Connolly ◽  
P. O'Connor ◽  
F. Buckley ◽  
...  
Keyword(s):  
Milk Production ◽  
North American ◽  
Milk Fat ◽  
Feeding System ◽  
Stocking Rate ◽  
Concentrate Supplementation ◽  
Herbage Intake ◽  
Biting Rate ◽  
Holstein Friesian ◽  
Grazing Behaviour

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< 0.01) and spent a lower proportion of time ruminating (P< 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< 0.001) than in the MP system. Heifers on HC had shorter grazing time (P< 0.01) with grazing bouts of shorter duration (P< 0.01). Increasing stocking rate (HS) decreased the proportion of time ruminating (P< 0.001) and tended to shorten grazing bouts (P = 0.06). The HP strain had higher (P< 0.05) herbage and total dry matter (DM) intakes than the NZ strain, while the HD strain was intermediate. Concentrate supplementation reduced (P< 0.001) herbage DM intake but increased (P< 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.

Performance of temperate perennial pastures in the Australian subtropics 2. Milk production

1999 ◽  
Vol 39 (6) ◽  
pp. 677 ◽  
Author(s):  
T. M. Bowdler ◽  
N. D. Casey ◽  
R. J. Moss ◽  
K. F. Lowe
Keyword(s):  
Milk Production ◽  
Perennial Ryegrass ◽  
Festuca Arundinacea ◽  
Italian Ryegrass ◽  
Perennial Grasses ◽  
Gross Margin ◽  
The Third ◽  
Holstein Friesian ◽  
Prairie Grass ◽  
Milk Component

Summary. Milk production from irrigated, pure stands of perennial ryegrass (Lolium perenne cv. Yatsyn), prairie grass (Bromus willdenodii cv. Matua) and tall fescue (Festuca arundinacea cv. AU Triumph) were compared with that achieved from Italian ryegrass (L. multiflorum cv. Concord) over 3 lactations of multiparous Holstein–Friesian cows at Mutdapilly in south-east Queensland. Pastures were fertilised with 50 kg nitrogen/ha . month as urea and annual dressings of 20 kg phosphorus/ha and 50 kg potassium/ha (as superphosphate and muriate of potash respectively). There were 4 pasture treatments grazed at 3 cows/ha in a 1-week-on, 3-weeks-off rotation with 2 replicates and 3 cows/treatment block. Cows grazed the pastures day and night from May to November. Over summer, cows grazed the pastures during the night and were fed supplements (silage in the first lactation, and lucerne hay in the second and third lactations) during the day because there was no shade available in the irrigation areas. In autumn, the animals were removed from the ryegrass and prairie grass pastures for 8 weeks to allow seedling re-establishment, either by oversowing (ryegrasses) or natural reseeding (prairie grass). Cows continued to graze the fescue pastures at night during autumn. All cows received a ration of 4 kg/cow of a grain–minerals mixture in the first lactation and 5 kg/cow in the second and third lactations. Milk production from perennial ryegrass was higher than from fescue in the first lactation and Italian ryegrass in the second and third lactations. Prairie grass gave similar milk production to perennial ryegrass in all 3 years. In the third year, perennial ryegrass, prairie grass and fescue gave similar milk production. Milk quality from the 4 grasses was similar except in the third lactation when the lactose content of milk from perennial ryegrass pastures was lowest. There were also small and inconsistent differences in milk component yields between the 4 grasses. Liveweight changes were small except in the second lactation when the cows grazing fescue lost weight relative to the other treatments. Mean liveweight at calving increased over the 3 lactations. It was concluded that all 3 temperate perennial grasses demonstrated useful traits for use in subtropical dairy pastures. Perennial ryegrass produced the most milk from the lowest amount of dry matter on offer. Prairie grass produced similar milk yields to perennial ryegrass, was well eaten by cattle and was self regenerating. Although fescue was slower to establish and needed more intensive management to control maturity, it was the most persistent and was the only grass to provide autumn grazing. In the second year this attribute resulted in a lower requirement for supplementary feeding. Fescue produced the highest gross margin in the second lactation and was only marginally less than prairie grass in the third. The performance of Italian ryegrass was as good as that of perennial ryegrass in the first lactation but fell substantially in the second and third lactations as the level of summer grass invasion increased.

Effect of timing of protein supplementation on the performance of lactating dairy cows

2005 ◽  
Vol 45 (4) ◽  
pp. 337
Author(s):  
B. C. Granzin
Keyword(s):  
Dairy Cows ◽  
Milk Production ◽  
Milk Fat ◽  
Protein Supplementation ◽  
Net Energy ◽  
Maize Silage ◽  
Holstein Friesian ◽  
Grazing Dairy Cows ◽  
And Control ◽  
Friesian Cows

Two experiments were undertaken to determine the effect of timing of protein supplementation on performance of grazing, lactating Holstein–Friesian cows fed maize silage and grain-based concentrate. In experiment 1, 36 cows were fed 0.8 kg DM/day of solvent-extracted cottonseed meal (CSM) either as 1 meal at 1200 hours with maize silage (CSM 1200) or at 1530 hours with concentrate (CSM 1530), or in 2 meals at 0600 and 1530 hours with concentrate (CSM 600 + 1530). In experiment 2, 36 cows were either fed no CSM (control) or fed 1.0 kg DM/day as either CSM 1200 or CSM 600 + 1530. In experiment 1, daily yields of 4% fat-corrected milk (FCM) and milk fat for CSM 600 + 1530 were significantly higher than for CSM 1530 with respective means of 22.8 v. 20.7 L and 895 v. 804 g. Daily yields of FCM and milk fat for CSM 1200 were intermediate (21.7 L and 841 g/cow, respectively). A similar trend for daily protein yield per cow was noted (712, 695 and 666 g for CSM 600 + 1530, 1200 and 1530, respectively). In experiment 2, milk yield differed numerically between CSM 600 + 1530 and other treatments, with means (± s.e.d.) of 24.7 ± 0.78, 22.9 ± 0.78 and 22.9 ± 0.78 L/cow.day for CSM 600 + 1530, CSM 1200 and control, respectively. Mean (± s.e.d.) net energy requirements for milk production and liveweight change tended to be lower for the control (68 ± 3.6 MJ/cow.day) as opposed to CSM 600 + 1530 (79 ± 3.6 MJ/cow.day) and CSM 1200 (76 ± 3.6 MJ/cow.day). Cumulative time where rumen degradable nitrogen:rumen degradable dry matter was less than 22 g/kg were 2, 2 and 3 h for CSM 600 + 1530, CSM 1200 and CSM 1530, respectively, in experiment 1, and 6, 4 and 2 h for the control, 1200 and CSM 600 + 1530, respectively, in experiment 2. No differences in rumen ammonia-N concentrations were noted between treatments in experiment 1. In experiment 2, a significantly lower mean (± s.e.d.) rumen ammonia-N concentration was recorded for the control at 1530 hours (62 ± 14.1 mg/dL) in comparison to CSM 600 + 1530 (114 ± 14.1 mg/dL) and CSM 1200 (119 ± 14.1 mg/dL). These experiments show that for grazing dairy cows supplemented with maize silage and grain-based concentrate, feeding a daily aliquot of CSM as 2 meals at 0600 and 1530 hours rather than 1 meal at 1200 or 1530 hours improves milk production.

scholarly journals Effect of concentrate supplementation during pre-kidding on the productive and reproductive performance of goats raised on Guinea grass (Panicum maximum cv. Tobiatã) pasture

2016 ◽  
Vol 37 (3) ◽  
pp. 1489
Author(s):  
Raquel Ornelas Marques ◽  
Heraldo Cesar Gonçalves ◽  
Paulo Roberto De Lima Meirelles ◽  
Gil Ignacio Lara Cañizares ◽  
Giuliana Micai de Oliveira ◽  
...  
Keyword(s):  
Birth Weight ◽  
Milk Production ◽  
Milk Fat ◽  
Panicum Maximum ◽  
Dry Extract ◽  
Concentrate Supplementation ◽  
Stage Of Lactation ◽  
Lactation Curve ◽  
Guinea Grass ◽  
Boer Goats

Sixty goats (20 Alpine, 18 Anglo-Nubian, and 22 crossbred Boer), with average body weight 49.33 ± 1.41 kg, were raised on Panicum maximum cv. Tobiatã pasture with two different levels of concentrate supplementation, 300 (SL30) and 600 g kg-1 (SL60) of the daily requirements, and evaluated from the pre-mating season until an average of 110 days of lactation. Milk controls were performed every 14 days. The following milk production curve parameters were estimated: time to reach peak milk production (TP), peak milk production (PP) and milk production during the first 110 days of lactation (MP). The following milk components were determined: fat, protein, lactose, total solids (TS), defatted dry extract (DDE), urea nitrogen (UN) concentrations, and somatic cell count (SCC). Goat prolificacy and birth weight of the kids were also determined. Breed affected the lactation curve, with Alpine and Anglo- Nubian goats presenting higher TP, PP, and MP. Protein, TS, and DDE concentrations were also affected by breed, being higher for crossbred Boer goats. Milk fat, lactose concentrations, and the log of SCC were affected by the concentrate supplementation level, being higher for SL30, as well as by the breed, with crossbred Boer goats presenting higher fat concentrations and log of SCC, and crossbred Boer and Alpine goats presenting higher lactose concentrations. UN was affected by the stage of lactation. Prolificacy and birth weight were affected by breed and concentrate supplementation level, being higher for Anglo-Nubian and crossbred Boer goats with SL60. Kids from single births presented higher birth weights. The Anglo-Nubian breed presented good milk production and the best body condition, which might indicate the effectiveness of this production system, SL60 supplementation resulted in higher birth weight and prolificacy.

scholarly journals L-selectin gene polymorphism and its association with clinical mastitis, somatic cell score, and milk production in Polish Holstein-Friesian cattle

2018 ◽  
Vol 63 (No. 7) ◽  
pp. 256-262 ◽  
Author(s):  
M. Dusza ◽  
J. Pokorska ◽  
J. Makulska ◽  
D. Kulaj ◽  
M. Cupial
Keyword(s):  
Somatic Cell ◽  
Milk Production ◽  
Milk Fat ◽  
Bacterial Infections ◽  
Clinical Mastitis ◽  
Somatic Cell Score ◽  
Production Traits ◽  
Milk Production Traits ◽  
Holstein Friesian ◽  
Friesian Cows

Bovine mastitis is a widespread disease of the mammary gland, highly contributing to the increase in veterinary costs in dairy industry. In the present study, the genetic polymorphism within bovine L-selectin gene was analysed and its impact on clinical mastitis occurrence, somatic cell score (SCS), and milk production traits in Polish Holstein-Friesian cows was examined. Polymorphism within L-selectin gene, molecule responsible for neutrophil attachment to endothelium, might have a potential role in immune response to bacterial infections and udder health. Two hundred and six Polish Holstein-Friesian cows were genotyped by polymerase chain reaction-restriction fragment length polymorphism method. Two single nucleotide polymorphisms mutations within the coding sequence of L-selectin gene were identified (c.165G&gt;A and c.567C&gt;T). The effect of c.165G&gt;A and c.567C&gt;T mutations on SCS was highly significant (P = 0.0019 and P = 0.0003, respectively). Strong associations (P ≤ 0.0001) were also observed between L-selectin polymorphism and milk production traits (milk yield, milk fat percentage, and milk protein percentage). However, the polymorphism in the analysed gene had no influence on the resistance or susceptibility of cows to clinical mastitis (only the tendency toward significance, P = 0.06 for c.567C&gt;T mutation was found). Potential exploitation of the information on the identified associations in genetic selection needs to confirm the obtained results in further investigations.

Milk production by dairy cows fed legume grains or barley grain with or without urea as supplements to a cereal hay based diet

1990 ◽  
Vol 30 (1) ◽  
pp. 7 ◽  
Author(s):  
SC Valentine ◽  
BD Bartsch
Keyword(s):  
Milk Production ◽  
Faba Bean ◽  
Milk Fat ◽  
Dry Matter ◽  
Milk Protein ◽  
Barley Grain ◽  
Early Lactation ◽  
Milk Protein Content ◽  
Holstein Friesian ◽  
Friesian Cows

Milk production and composition was determined in Holstein-Friesian cows fed either 3.5 or 7.0 kg dry matter (DM) daily of lupin grain, pea grain, faba bean grain or barley grain with or without 1.5% added urea, as supplements to an oaten hay based diet. All the grains were hammermilled. Daily yields of milk (L), fat (kg) and protein (kg) were significantly (P<0.05) higher for cows fed lupin (20.0, 0.81, 0.57), pea (18.9, 0.80, 0.56) and faba bean (18.9, 0.79,0.55) grains compared with those of cows fed barley grain with (17.8, 0.73, 0.51) or without (18.0, 0.71, 0.52) urea. Yields of milk (L), fat (kg) and protein (kg) and milk protein content (g/kg) were significantly (P<0.05) higher when 7.0 kg DM (19.5, 0.80, 0.57, 29.6) compared with 3.5 kg DM (18.0,0.73,0.51,29.0) of grain was fed. There were no significant differences between treatments in hay DM intake by cows fed 3.5 kg DM of grain daily. A significantly (P<0.05) higher milk fat production per unit DM intake was recorded for cows fed legume compared with barley grain. There were generally higher returns above grain cost for cows fed legume compared with barley grain and for cows fed 4 kg compared to 8 kg daily of grain. It was concluded that it was more economical to feed 3.5 kg DM of legume grain compared with 3.5 kg DM of barley grain, with or without urea, as supplements for cows offered cereal hay in early lactation. However, the economics of feeding 7.0 kg DM of legume grain compared with 7.0 kg DM of barley grain and 7.0 kg DM compared with 3.5 kg DM of grain will depend on the costs of relative changes in hay intake associated with these practices.

ПРОДУКТИВНОСТЬ КОРОВ ХОЛМОГОРСКОЙ ПОРОДЫ С РАЗЛИЧНОЙ СТЕПЕНЬЮ ГОЛШТИНИЗАЦИИ В УСЛОВИЯХ РЕСПУБЛИКИ КОМИ

2020 ◽  
Author(s):  
S.V. NIKOLAEV ◽  
N.A. SHEMURANOVA
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Milk Fat ◽  
Komi Republic ◽  
Fat Content ◽  
Milk Productivity ◽  
Blood Content ◽  
Holstein Breed ◽  
The Third ◽  
Economic Use

Представлены данные о продуктивности коров холмогорской породы и их помесей с различной степенью голштинизации. В период с 2000 по 2019 год установлено, что в условиях Республики Коми коровы с долей кровности более 75 по голштинской породе превосходят чистопородный холмогорский скот по показателям молочной продуктивности и жира в молоке за 1-ю лактацию на 40,3 и 0,63 абс., а в 3-ю на 52,8 и 0,64 абс., соответственно. Однако повышение молочности за лактацию не приводит к увеличению пожизненного производства молока, что обусловлено снижением продолжительности хозяйственного использования. У коров с долей кровности по голштинам более 75 средний возраст выбытия составляет 2,400,11 отела, что в 1,5 раза меньше по сравнению с чистопородными животными.Наибольший пожизненный удой имеют животные с кровностью 50, полученные при скрещивании чистопородного голштинского и холмогорского скота (19850618 кг), а наименьший с кровностью 2550 при разведении помесей в себе (123281134 кг). Продукция молочного жира за все лактации у коров с кровностью 50 составляет 799,625,3 кг, что в 1,9 раз больше аналогичного показателя животных с долей кровности до 25. При учете молочной продуктивности на 1 день жизни животного установлено, что наибольший показатель наблюдается у коров с кровностью 50 7,4 кг молока натуральной жирности, а при пересчете на базисную жирность (3,4) у высококровных (более 75) по голштинской породе помесей (9,00,3 кг), где также наблюдается наибольший показатель производства молочного жира на 1 день жизни 307,310,1 г.The article presents data on the productivity of cows of the Kholmogorskaya breed and their crosses with varying degrees of holsteinische. In the course of studies conducted in the period from 2000 to 2019, it was found that in the Komi Republic, cows with a blood content of more than 75 of the Holstein breed outperform pure-bred Kholmogorsky cattle in terms of milk productivity and fat in milk for the first lactation by 40.3 and 0.63, and in the third by 52.8 and 0.64 respectively. However, an increase in milk yield per lactation does not lead to an increase in lifetime milk production, which is due to a decrease in the duration of economic use: in cows with a Holstein blood ratio of more than 75, the average leaving age is 2.400.11 calving, which is 1.5 times less than in purebred animals. The highest lifetime yield is given to animals with a blood content of 50 obtained by crossing Chi-pedigree Holstein and Kholmogorsky cattle (19850618 kg), and the lowest with a blood content of 2550 when breeding crossbreeds in themselves (123281134 kg). The production of milk fat during all lactation in cows with a blood content of 50 is 799.625.3 kg, which is 1.9 times more than in animals with a blood content of up to 25. When accounting for milk production on a day in the life of an animal is established that the highest milk yield observed in cows with percentage of the blood 50 and 7.4 kg of milk, natural fat content, and at recalculation on basic fat content (3.4) from 75 of the Holstein breed hybrids (9.00.3 kg), which also has the highest production of milk fat on day 1 of life 307.310.1 grams

scholarly journals Single nucleotide polymorphisms at the imprinted bovine insulin-like growth factor 2 (IGF2) locus are associated with dairy performance in Irish Holstein-Friesian cattle

2010 ◽  
Vol 78 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Erik W Berkowicz ◽  
David A Magee ◽  
Klaudia M Sikora ◽  
Donagh P Berry ◽  
Dawn J Howard ◽  
...  
Keyword(s):  
Body Size ◽  
Growth Factor ◽  
Single Nucleotide Polymorphisms ◽  
Dairy Cattle ◽  
Milk Production ◽  
Milk Fat ◽  
Milk Protein ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Holstein Friesian

The imprinted insulin-like growth factor 2 gene (IGF2) encodes a fetal mitogenic hormone protein (IGF-II) and has previously been shown to be associated with performance in dairy cattle. In this study we assessed genotype-phenotype associations between four single nucleotide polymorphisms (SNPs) located within the bovine IGF2 locus on chromosome 29 and a range of performance traits related to milk production, animal growth and body size, fertility and progeny survival in 848 progeny-tested Irish Holstein-Friesian sires. Two of the four SNPs (rs42196909 and IGF2.g-3815A>G), which were in strong linkage disequilibrium (r2=0·995), were associated with milk yield (P⩽0·01) and milk protein yield (P⩽0·05); the rs42196901 SNP was also associated (P⩽0·05) with milk fat yield. Associations (P⩽0·05) with milk fat percentage and milk protein percentage were observed at the rs42196901 and IGF2.g-3815A>G SNPs, respectively. The rs42196909 and IGF2.g-3815A>G SNPs were also associated with progeny carcass conformation (P⩽0·05), while an association (P⩽0·01) with progeny carcass weight was observed at the rs42194733 SNP locus. None of the four SNPs were associated with body size, fertility and progeny survival. These findings support previous work which suggests that the IGF2 locus is an important biological regulator of milk production in dairy cattle and add to an accumulating body of research showing that imprinted genes influence many complex performance traits in cattle.

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