Reproductive function in average and high yielding dairy cows

AbstractThe resumption of reproductive activity in the early post partum period and the subsequent fertility of dairy cows are of considerable practical and economic importance to the producer. Regular milk progesterone analysis was used in this study to monitor the re-establishment of reproductive cyclicity in animals of average (AGM, n=20) and high genetic merit (HGM, n=28) kept under standard management conditions. The profiles obtained were then characterised into normal and four different types of abnormal activity. Resumption of cycles occurred significantly later in the higher yielding cows than in those of average genetic merit (23 ±2.3 days in HGM cows and 15 ± 1.6 days in AGM cows; P=0.0089). There was a significant increase in the amount of abnormal cycles encountered in the high genetic merit animals compared with average yielding animals (61% and 30% respectively; χ2 test, P=0.045); in particular, the delayed occurrence of ovulation post partum (11% vs 0%) and an increased incidence of persistent corpora lutea (32% vs 20%). For high genetic merit animals, the incidence of abnormal cycles was associated with increased peak milkyields (abnormal cycles: peak milk yield 54.7 ± 1.11 kg/day; normal cycles: peak milk yield 46.4 ± 1.35 kg/day, P=0.002). This relationship was not apparent in average genetic merit animals. First service conception rates were 50% (9/18) for AGM cows and 38% (10/26) for HGM cows (χ2 test, n.s.). The calving to conception interval was 98 ± 9.7 days for AGM animals (n=l7) and 105 ± 9.1 days for HGMs (n=24) (t-test, n.s.). In conclusion, this study confirms that high genetic merit dairy cows have compromised reproductive function in terms of a delayed resumption of cyclicity and an increased incidence of abnormal progesterone cycles, which was associated with higher peak milk yields. There was also a reduced first service conception rate in high yielders although the difference was not significant with this group size.

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Effect of dietary-induced increases in circulating insulin concentrations during the early postpartum period on reproductive function in dairy cows

Reproduction ◽

10.1530/rep.0.1230419 ◽

2002 ◽

pp. 419-427 ◽

Cited By ~ 138

Author(s):

JG Gong ◽

WJ Lee ◽

PC Garnsworthy ◽

R Webb

Keyword(s):

Body Weight ◽

Dairy Cows ◽

Milk Yield ◽

Body Condition ◽

Reproductive Performance ◽

Body Condition Score ◽

Post Partum ◽

Dietary Treatment ◽

Genetic Merit ◽

Selection For

Although it has become increasingly clear that fertility in modern dairy cattle is declining in association with increased milk yields, the underlying mechanism is poorly understood. The first ovulation post partum is delayed in dairy cows undergoing selection for genetic merit for milk yield in association with lower circulating insulin concentrations. The aim of this study was to investigate whether feeding a diet to increase circulating insulin concentrations can overcome this delay in the first ovulation post partum. The experiment was a 2 x 2 factorial design (n = 10 per group) involving diet and genetic merit for milk yield. The dietary treatment started on the day of calving and lasted for 50 days. Plasma samples were collected each day and ovarian ultra-sonography was performed three times a week during the experimental feeding period. Milk yield was recorded each day, and body weight and body condition score were determined each week. Milk samples were collected three times a week from day 50 to day 105 post partum, and reproductive performance data were recorded for all the cows as part of the routine farm practice. The dietary treatment induced significant differences in plasma insulin concentrations in both high and low genetic merit cows. Although high genetic merit cows produced more milk, lost more body weight and had lower body condition scores during the experiment, no significant effect of diet was observed on these measurements. The high insulin inducing diet increased the proportion of cows ovulating within 50 days of calving and reduced the intervals from calving to first ovulation, and tended to reduce the intervals from calving to first service and to conception. These fertility parameters were also more favourable in low than in high genetic merit cows, but no interaction between diet and genetic merit was observed for any of these parameters. Genetic merit, but not diet, also affected the number of services required per conception and the conception rate. In conclusion, these results have confirmed that genetic selection for high milk yield is associated with a decrease in reproductive performance in dairy cows. More importantly, this study has demonstrated that it is possible to alleviate this problem by nutritional manipulation.

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Physiological Adaptations to Milk Production that Affect the Fertility of High Yielding Dairy Cows

BSAP Occasional Publication ◽

10.1017/s0263967x00040040 ◽

2004 ◽

Vol 29 ◽

pp. 37-71 ◽

Cited By ~ 4

Author(s):

V. J. Taylor ◽

D. E. Beever ◽

D. C. Wathes

Keyword(s):

Dairy Cows ◽

Milk Production ◽

Ovarian Function ◽

Post Partum ◽

Reproductive Function ◽

Influential Factors ◽

Corpora Lutea ◽

Expected Time ◽

Physiological Adaptations ◽

Igf I

SummaryThe high yielding dairy cow is expected to produce a substantial milk output every year and at the same time to conceive and maintain a pregnancy to term. To fulfil lifetime production potential a balance between yield, fertility and other influential factors has to be achieved. Any inability on the part of the management system to identify and rectify problems or on the part of the cow to cope with metabolic demands invariably results in economic or welfare issues. Our studies of high yielding dairy cows have revealed that some animals are capable of normal reproductive function whilst others are classic repeat breeders (requiring 3+ services per conception) or simply fail to rebreed. It is well established that the somatotrophic axis (growth hormone and insulin-like growth factors) drives lactation in ruminants but it is also intimately involved in reproductive processes. An awareness of metabolic adaptations to lactation that impact on reproduction in dairy cows is needed for appropriate management.The objective of our studies was to explore the metabolic profiles of high yielding dairy cows to identify factors influencing their ovarian function and fertility, hence to characterise the physiological adaptations involved. Our studies revealed different relationships between progesterone profile categories and metabolic status post partum. Delayed ovulation (DOV) or persistent corpora lutea (PCL) may be an appropriate response to a nutritional state or physiological situation and it may therefore be inaccurate to refer to these as ‘abnormal’. Whilst associated with high milk yields, not all profile categories detrimentally affected fertility parameters. Delayed ovulation postcalving (DOV1) was identified as the most prevalent abnormal profile encountered in first lactation high yielding cows. This may have occurred because the cows were not yet physically mature and unable to sustain both milk production and growth. The condition lasted long enough (71 ± 8.3 days from calving) to have a detrimental impact on their overall fertility parameters and was associated with significant physiological changes, representative of tissue mobilisation. Although the incidence of persistent luteal phases (PCL1 and PCL2) in dairy cows is increasing, this condition was not found to have any substantial detrimental effects on fertility or production parameters of the primiparous or multiparous cows in these studies. The main reproductive problems in our high yielding primiparous and multiparous cows appeared to be a failure to ovulate and conceive at the expected time or to maintain a pregnancy. These situations were associated predominantly with high milk yields and low concentrations of plasma IGF-I. A failure to ovulate appears to occur when body reserves are mobilised to maintain milk yield at the expense of reproduction and seems most likely to occur in primiparous high yielding cows or those experiencing GH-resistance (low IGF-I) due to excessive body condition loss, reduced feed intakes and factors such as stress and disease. More detailed investigations of dietary means of increasing IGF-I and optimising insulin concentrations, targeted at important reproductive times, are required in high yielding dairy cows, to aid in their management.

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Effects of calcium salts of fatty acids on follicular characteristics and several blood parameters in two fat-tailed sheep breeds

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200007870 ◽

2002 ◽

Vol 2002 ◽

pp. 131-131

Author(s):

M. J. Zamiri ◽

E. Rowghani ◽

S. M. Ghoreishi

Keyword(s):

Fatty Acids ◽

Plasma Cholesterol ◽

Post Partum ◽

Reproductive Function ◽

Blood Parameters ◽

Dietary Lipid ◽

Ovarian Activity ◽

Corpora Lutea ◽

Luteal Function ◽

Sheep Breeds

There is substantial evidence that the increased consumption of fat by dairy cattle can result in an increase in the number ovarian follicles, and the number and size of corpora lutea; it also stimulates post-partum ovarian activity and improve pregnancy rate. Increased dietary lipid also increases plasma cholesterol and progesterone, and the supply of lipoproteins which play significant roles in regulating ovarian steroidogenesis (Willimas, 1996). In contrast to cattle, there are few observations on the effects of dietary lipid on reproductive function in sheep. Intravascular infusion of lipid into ewes stimulated progesterone and prostaglandin synthesis (Burke et al., 1996), and dietary supplementation of calcium soaps of fatty acids enhanced luteal function (Kuran et al., 1999). Calcium soaps of fatty acids have been manufactured in Iran in recent years and sold under the trade name of Megalac. The aim of the present experiment was to study the effects of this protected fat on follicular number and luteal activity in two fat-tailed sheep breeds.

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Differences in the behaviour of high and low yielding dairy cows selected by genetic merit

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200008760 ◽

2002 ◽

Vol 2002 ◽

pp. 220-220 ◽

Cited By ~ 1

Author(s):

M.D. Cooper ◽

D. R. Arney ◽

C. J. C. Phillips

Keyword(s):

Coping Strategies ◽

Dairy Cows ◽

Milk Production ◽

Milk Yield ◽

Dairy Cow ◽

Detrimental Effect ◽

Genetic Merit ◽

High Nutrient

The effects of high milk yields on the behaviour and welfare of the dairy cow are unclear. A high milk yield increases the need to consume sufficient fodder in an attempt to meet high nutrient demands. The failure to meet the demands may result in persistent hunger in the dairy cow having to modify her behaviour by employing various coping strategies. These modifications may help the cow overcome a state of hunger but at the expense of being unable to express other important behaviours. The objective of this study was therefore to determine whether the behaviour and welfare of the genetically high yielding dairy cow is being compromised by the increased nutritional demands of milk production, and to investigate the possibility that an increased amount of time spent in food-directed behaviours may have a detrimental effect on the time available to perform other important behaviours.

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Effects of Extruded Linseed and Soybean Dietary Supplementation on Lactation Performance, First-Service Conception Rate, and Mastitis Incidence in Holstein Dairy Cows

Animals ◽

10.3390/ani10030436 ◽

2020 ◽

Vol 10 (3) ◽

pp. 436

Author(s):

Ahmed Dawod ◽

Hamada Ahmed ◽

Reham Abou-Elkhair ◽

Hamed T. Elbaz ◽

Ayman E. Taha ◽

...

Keyword(s):

Fatty Acids ◽

Dairy Cows ◽

Milk Yield ◽

Unsaturated Fatty Acids ◽

Saturated Fatty Acids ◽

Dietary Supplementation ◽

Basal Diet ◽

Conception Rate ◽

Service Conception ◽

Holstein Dairy Cows

This study quantifies the effects of extruded linseed and soybean (ELS) dietary supplementation on milk yield, composition, and fatty acid profiles, as well as first-service conception rate in Holstein dairy cows. Seventy-eight open Holstein dairy cows were divided into two groups: (1) a control, which received a basal diet; and (2) a test group, which received a basal diet supplemented with the ELS (650 g/kg of extruded linseed and 150 g/kg of extruded soybean) at a rate of 100 g/kg. In the ELS group, milk yield per day and solid not fat (SNF) yield increased by 3.26% and 0.88%, respectively, in relation to the control. Percentage milk fat decreased significantly by 1.4% in the ELS group when compared with the control. The ELS supplement resulted in a decrease in saturated fatty acids (SFAs) and an increase in monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs) in milk. In conclusion, the supplementation of dairy cow feed with 100 g/kg of ELS increases milk yield and milk unsaturated fatty acids (especially MUFAs and PUFAs). ELS supplementation also causes a decrease in percentage fat and SFA levels but does not affect the first-service conception rate or the incidence rate of mastitis.

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Effect of genetic merit, milk yield, body condition and lactation number on in vitro oocyte development in dairy cows

Theriogenology ◽

10.1016/s0093-691x(00)00244-2 ◽

2000 ◽

Vol 53 (4) ◽

pp. 981-989 ◽

Cited By ~ 88

Author(s):

S.E.M. Snijders ◽

P. Dillon ◽

D. O'Callaghan ◽

M.P. Boland

Keyword(s):

Dairy Cows ◽

Milk Yield ◽

Body Condition ◽

Oocyte Development ◽

Genetic Merit

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Consequences for reproductive function of metabolic adaption to load

BSAP Occasional Publication ◽

10.1017/s1463981500043119 ◽

1999 ◽

Vol 24 ◽

pp. 99-112 ◽

Cited By ~ 8

Author(s):

R. Webb ◽

P. C. Garnsworthy ◽

J. G. Gong ◽

R. S. Robinson ◽

D. C. Wathes

Keyword(s):

Energy Balance ◽

Dairy Cows ◽

Milk Production ◽

Direct Effect ◽

Milk Yield ◽

Dairy Cow ◽

Reproductive Function ◽

Negative Energy ◽

Follicular Growth ◽

Embryo Survival

AbstractAn effective method for enhancing milk production efficiency in dairy cows is to increase milk yield and significant progress has been achieved through intense selection, assisted by the application of new reproductive techniques. However this increased milk yield has been accompanied by a slow but steady decline in dairy cow fertility. The two main reasons for this reducing level of fertility appear to be selection for increased milk yield and large herd sizes, although the affect of the introduction of Holstein genes needs to be investigated. In addition, other negative consequences such as an increase in the incidence of metabolic diseases and lameness have been observed. This has given rise to public concern that the high-yielding dairy cow may be under a state of metabolic stress during peak lactation and therefore the welfare and performance of other body functions are compromised.The reason for this decline in fertility is not well understood, although a nutritional influence on the initiation of oestrous cycles, follicular growth, oocyte quality and early embryonic development has been implicated. In early lactation dietary intake is unable to meet the demands of milk production and most cows enter a period of negative energy balance. Negative energy balance has a broadly similar effect to undernutrition leading to a mobilization of body reserves. Furthermore diets high in rumen degradable protein lead to an excess of rumen ammonia, which before it is converted to urea by the liver and excreted in the urine, may cause an alteration in the reproductive tract environment reducing embryo survival. Such major changes in the metabolic and endocrine systems can therefore influence fertility at a number of key points.Possible reproductive sites where inadequate nutrition may have detrimental effects include: (i) the hypothalamic/pituitary gland where gonadotropin release may be impaired; (ii) a direct effect on the ovaries, where both follicular growth patterns and corpus luteum function may be directly influenced; (iii) the quality of the oocyte prior to ovulation may be reduced and coupled with an inadequate uterine environment will result in reduced embryo survival and (iv) there may be effects on subsequent embryo development. The initiation of normal oestrous cycles post partum is usually delayed in dairy cows with a higher genetic merit for milk production, confirming that intense selection towards high milk yield can compromise reproductive function. In addition, the effects of increased milk yield may include changes in circulating GH and insulin concentrations, which in turn alter both insulin-like growth factor (IGF) and IGF binding protein production. Nutrition has recently been shown to have a direct effect at the level of both the ovaries and the uterus to alter the expression of these growth factors.In conclusion, further knowledge is required to determine how the metabolic changes associated with high milk output reduce fertility. Identification and understanding of the mechanisms involved and the key sites of action responsible for compromised reproductive function, will enable the identification of possible indices for future multiple-trait selection programmes.

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The influence of cow genetic merit for milk production on response to level of concentrate supplementation in a grass based system

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200012163 ◽

2003 ◽

Vol 2003 ◽

pp. 57-57 ◽

Cited By ~ 1

Author(s):

P. Dillon ◽

J. Kennedy ◽

P. Faverdin ◽

L. Delaby ◽

F. Buckley ◽

...

Keyword(s):

Dairy Cows ◽

Milk Production ◽

Milk Yield ◽

Yield Potential ◽

Genetic Merit ◽

Concentrate Supplementation ◽

Holstein Friesian

Pre-1990 published responses to supplementation at pasture ranged from 0.4 to 0.6kg milk/kg concentrate fed. However since 1990 higher responses to concentrate supplementation at pasture have been published (Delaby 2001). The objective of this study was to determine if milk production responses of Holstein-Friesian dairy cows to concentrate supplementation at pasture are influenced by genetic merit (milk yield potential) in a spring calving grass based system of milk production.

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The responses of high and medium merit dairy cows to diets differing in grass silage: concentrate ratios, during early lactation

Proceedings of the British Society of Animal Science ◽

10.1017/s0308229600029810 ◽

1996 ◽

Vol 1996 ◽

pp. 5-5

Author(s):

C.P. Ferris ◽

F.J. Gordon ◽

D.C. Patterson ◽

C.S. Mayne

Keyword(s):

Dairy Cows ◽

Milk Yield ◽

Dairy Herd ◽

Yield Potential ◽

Genetic Merit ◽

The Past ◽

Grass Silage ◽

The Uk ◽

Yield Responses ◽

Feeding Systems

The genetic merit of the UK dairy herd is increasing rapidly and this trend is likely to continue for the forseeable future. With cows of higher milk yield potential and higher nutrient requirements, feeding systems developed in the past with medium genetic merit animals, may now need to be adapted to meet the needs of high genetic merit animals if nutrition x genotype interactions exist. This would be particularly true to increasing proportion of concentrates in grass silage based diets. This study was undertaken to compare the milk yield responses of high and medium merit dairy cows.

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