Evaluation of the impact of a Herd Health and Production Management programme in organic dairy cattle farms: a process evaluation approach

Animal health planning activities are not always providing a satisfactory positive impact on herd health and welfare. Moreover, evaluating the impact of advisory programmes is complex due to multiple interacting elements that influence its outcome. Therefore, measuring solely health outcomes is not sufficient: the whole process of the implementation and use of such programmes should be evaluated. In order to evaluate the impact of an intervention with a Herd Health and Production Management (HHPM) programme a process evaluation framework was designed and used. The intervention involved 20 organic dairy cattle farmers and their advisors, in both France and Sweden. In both countries 20 organic dairy farms were selected as control herds. The evaluation of the HHPM programme was based on: (a) the compliance to the programme; (b) the programme’s functions influencing herd health management practices and stimulating dialogue between farmers and advisors; (c) its effectiveness in terms of improving herd health compared with control farms. Complete compliance to the programme was fulfilled by 21 out of 40 farmers–advisors. Results from a questionnaire showed that the programme functioned as intended (e.g. by allowing early identification of herd health problems), stimulated change in farmers’ herd health management practices and farmer–advisor dialogue. Even though the majority of the users perceived that the programme contributed to herd health improvements, no significant differences in health outcomes were found when compared with control farms 12 months after the start of the intervention. The programme allowed creating an environment promoting the exchange of information between farmers and advisors, necessary to define pertinent advice in a farm-specific situation. Future research should aim at improving methods for the evaluation of the effect of advisory programmes, by identifying early indicators for effective advice and developing methods to evaluate the quality of advisory situations without interfering with them.     

The impact of controlled nutrition during the dry period on dairy cow health, fertility and performance

Average dairy herd fertility is declining, with more serves per successful conception, extended calving intervals and increased culling due to failure to rebreed, all adding significant costs to milk production. Genetics, management and nutrition have all contributed to this decline in fertility; the paper focuses primarily on nutritional issues. The extent of body condition loss after calving and its possible impact on fertility is considered, with evidence that this phenomenon is common in many herds irrespective of average milk yields. Body tissue mobilisation after calving increases the flux of non-esterified fatty acids to the liver and pathways of fatty acid metabolism are considered. Particular attention is given to the effects of high plasma non-esterified fatty acid levels on fat accumulation in liver cells and possible impacts on nitrogen and glucose metabolism. Current nutritional practices with early lactation cows which aim to stimulate milk yield and peak milk production but have been shown to exacerbate body condition loss, are reviewed. The paper also considers cow health issues during the peri-parturient period and how these may affect milk yield and fertility. It is concluded that current feeding practices for dry cows, with the provision of increasing amounts of the lactation ration during the Close-up period to accustom the rumen microbes and offset the expected reduction in feed intake as pregnancy reaches term, have largely failed to overcome peri-parturient health problems, excessive body condition loss after calving or declining fertility. From an examination of the energy and protein requirements of dry cows, it is suggested that current Close-up feeding practices can lead to luxury intakes of nutrients that can increase fat deposition in the viscera and the liver. Under such conditions, metabolism of nutrients by the cow may be compromised. In contrast, limited feeding throughout the whole dry period has been shown to prevent many of the problems which can affect peri-parturient cows. A new feeding strategy based on a low energy: high fibre ration (9 MJ metabolisable energy and 130 g crude protein/kg ration dry matter) containing high levels of chopped straw and offered ad libitum as a total mixed ration throughout the whole dry period is proposed. The performance of 32 dairy farms in France where this strategy has been adopted for at least 3 years is provided, with positive outcomes now being obtained by UK and Irish dairy farmers. Independent US research evidence has confirmed some of these benefits whilst limited data on cow fertility is presented. It is hypothesised that luxury feeding during the dry period can cause cows to become insulin resistant leading to an increased risk of type II diabetes. Such cows are likely to have poorer fertility whilst possible mechanisms which increase the risk of peri-parturient health problems are discussed. Further research to understand the mechanisms of these effects is required and is currently ongoing. However the magnitude of the effects noted on an increasing number of dairy farms suggests this approach to feeding the dry cow is capable of bringing real benefits to many dairy herds in terms of fewer health problems, reduced body condition loss and improved fertility.     

Extent, pattern and factors associated with late embryonic loss in dairy cows

Intensive genetic selection for increased milk production, coupled with increased dry matter intakes has led to significant improvements in cow milk yield, however, this increase in milk output has been accompanied by a decline in cow fertility. It has been suggested that there is a higher increment of late embryonic loss in high-yielding than in moderate yielding cows or in heifers. The objectives of this study were to establish the extent and pattern of embryonic loss, from days 28 to 84 of gestation, and to examine possible relationships between cow milk yield, cow genetic merit, parity, calving to insemination interval and embryonic loss in dairy cows managed mainly under pasture-based milk production systems. Multiparous dairy cows (n=1046) located on 8 farms and nulliparous dairy heifers (n=162) located on five of these farms were used in this study. The extent and timing of embryonic loss was measured by ultrasound scanning of the cows and heifers at 14-day intervals between days 28 and 84 of gestation. Positive diagnosis of pregnancy was based on the presence of an embryo or foetus with a visible heartbeat and, at the later scans, visible movement, whose size was compatible with stage of gestation and also on the presence of clear amniotic fluid of the cows and heifers presented as presumed pregnant on day 28 after insemination, 67 and 81%, respectively had a viable embryo. The subsequent embryonic loss rate between days 28 and 84 of gestation was similar (P>0.05) for cows (7.2%) and heifers (6.1%) and the pattern of loss over this period was also similar (P>0.05) for cows and heifers. There was no significant association (P>0.05) between level of milk production or milk energy output measured to day 120 of lactation and embryonic loss rate. Similarly, there was no significant relationship (P>0.05) between % milk fat, % milk protein and % milk lactose and embryonic loss rate. The extent and pattern of embryonic loss were not related (P>0.05) to either cow or to cow sire genetic merit. There was no significant (P>0.05) relationship between the calving to first service interval and embryonic loss. The extent of embryonic loss was greater (P<0.05) in cows that lost body condition between days 28 and 56 of gestation compared with cows than either maintained or improved in body condition.     

Determinations of feed–milk–manure relationships on grazing-based dairy farms

Feed conversion into milk, nutrient excretion in manure and subsequent environment impacts of manure management are highly influenced by the diets that farmers feed their lactating cows (Bos taurus). On confinement-based dairy farms, determinations of diet composition are relatively straightforward because the types, amounts and nutrients contained in stored feeds are often well known. However, on grazing-based dairy farms, diet composition is more difficult to determine because forage intake during grazing must be estimated. The objectives of this study were to determine relationships between (1) feed N intake (NI), milk production, milk urea N (MUN), feed N use efficiency (FNUE) and excreted manure N (ExN); and (2) between feed P intake (PI), dung P concentrations (g/kg dry matter (DM)) and excreted manure P (ExP) for grazing-based lactating cows having a very wide range of diets and milk production. An additional objective was to evaluate how well these relationships compare with similar relationships based on more direct measurement of feed–milk–manure on confinement-based dairy farms. Four dairy farms located in southeastern Australia were visited during autumn and spring, and data were collected on feed, milk and dung of 18 cows on each farm. Estimated dry matter intake (DMI) from pasture comprised 12% to 75% of total diet DMI, and the crude protein (CP) concentrations in the total diets ranged from 167 to 248 g/kg. During spring, as diet CP increased FNUE declined. Total diet DMI and NI provided the best predictors of ExN, and PI provided the most accurate prediction of ExP. These results indicated accuracy in the study's indirect estimates of pasture DMI. Likely due to high levels and great variability in dietary CP and P concentrations associated with use of diet supplements, MUN did not appear to be a good indicator of dietary CP, and P in dung was not a good indicator of dietary P.     

Effects of forage NDF content and body condition score on forage intake by Holstein-Friesian dairy cows in the dry period

This study used individual weekly results for 160 non-lactating Holstein-Friesian dairy cows in the last 5 weeks of gestation to develop regression equations based on forage NDF content and individual body condition score (BCS) for predicting dry matter (DM) intake. Results were used from treatments in which cows received the same forage and no concentrates throughout the dry period. Ten different conserved forages, either grass silages or mixtures of grass silage and barley straw, were fed in six different experiments and forage NDF ranged from 452 to 689 g/kg DM. On average cows gained 390 g live weight per day, which is less than conceptus growth at this stage - suggesting some mobilisation of maternal tissues to support conceptus growth. BCS remained unchanged at 2.5 over the dry period. DM intake declined from 10.79 kg/day 5 weeks before calving to 9.32 kg/day in the week before calving, with half of this decline occurring in the final week before calving. Intake as a percentage of live weight was moderately predicted (R2 = 0.61 for the entire period) from measures of diet composition (NDF) and cow state (BCS). There were highly significant negative effects of forage NDF and increased BCS on DM intake. The effect of BCS on DM intake was greatly reduced in the week before calving, possibly as a result of a change in metabolic priorities from gaining to losing body reserves.     

Using milk urea nitrogen to evaluate diet formulation and environmental impact on dairy farms

Reducing nitrogen (N) excretion by dairy cattle is the most effective means to reduce N losses (runoff, volatilization, and leaching) from dairy farms. The objectives of this review are to examine the use of milk urea nitrogen (MUN) to measure N excretion and utilization efficiency in lactating dairy cows and to examine impacts of overfeeding N to dairy cows in the Chesapeake Bay drainage basin. A mathematical model was developed and evaluated with an independent literature data set to integrate MUN and milk composition to predict urinary and fecal excretion, intake, and utilization efficiency for N in lactating dairy cows. This model was subsequently used to develop target MUN concentrations for lactating dairy cattle fed according to National Research Council (NRC) recommendations. Target values calculated in this manner were 8 to 14 mg/dl for a typical lactation and were most sensitive to change in milk production and crude protein intake. Routine use of MUN to monitor dairy cattle diets was introduced to dairy farms (n = 1156) in the Chesapeake Bay watershed. Participating farmers (n = 454) were provided with the results of their MUN analyses and interpretive information monthly for a period of 6 months. The average MUN across all farms in the study increased in the spring, but the increase was 0.52 mg/dl lower for farmers receiving MUN results compared to those who did not participate in the program. This change indicated that participating farmers reduced N feeding compared to nonparticipants. Average efficiency of feed N utilization (N in milk / N in feed x 100) was 24.5% (SD = 4.5). On average, farmers fed 6.6% more N than recommended by the NRC, resulting in a 16% increase in urinary N and a 2.7% increase in fecal N compared to feeding to requirement. N loading to the Chesapeake Bay from overfeeding protein to lactating dairy cattle was estimated to be 7.6 million kg/year. MUN is a useful tool to measure diet adequacy and environmental impact from dairy farms.     

Relationship between incidence of milk fever and feeding of minerals during the last 3 weeks of gestation

This study evaluated whether differences in milk fever incidence among Swedish dairy herds could be explained partly by differences in mineral feeding during the last weeks of gestation. A case–control study was performed on dietary risk factors for a high incidence of milk fever at the herd level using information regarding feeding and management of the dry cows collected in a written questionnaire distributed by post in spring 2008. The study was conducted from September 2004 to August 2007. Data on the diets fed to dry cows, with an emphasis on the amounts of minerals (Ca, P, Mg and K) fed 3 weeks before calving and at calving, were obtained from 30 herds belonging to the 100 Swedish herds with the highest recorded incidence of veterinary treatment for milk fever (>8.8%) and from 22 herds with no recorded milk fever treatments. Multivariable logistic regression analysis showed that a linear increase in the total amount of K and less than 26 g of Mg/day fed to dry cows 3 weeks before calving was associated with an increased risk of high milk fever incidence. A large increase in the amount of dry matter (DM) fed (>3.1 kg DM extra per day at calving compared with 3 weeks before calving) was associated with a higher incidence of milk fever, but no differences were found for Ca or P intake. Breed composition, herd average milk yield and age composition of the herd did not explain any of the observed differences between the case and the control herds. The results indicate that differences in the frequency of milk fever among herds can be associated with differences in mineral feeding of the dry cows. A high amount of K in the diet may increase the risk of milk fever linearly, whereas Mg should probably be fed at a higher level than the current Nordic recommendation to prevent milk fever.     

Effect of Supranutritional Organic Selenium Supplementation on Postpartum Blood Micronutrients,Antioxidants, Metabolites,and Inflammation Biomarkers in Selenium-Replete Dairy Cows

Dairy cows have increased nutritional requirements for antioxidants postpartum. Supranutritional organic Se supplementation may be beneficial because selenoproteins are involved in regulating oxidative stress and inflammation. Our objective was to determine whether feeding Se-yeast above requirements to Se-replete dairy cows during late gestation affects blood micronutrients, antioxidants, metabolites, and inflammation biomarkers postpartum. During the last 8-weeks before calving, dairy cows at a commercial farm were fed either 0 (control) or 105 mg Se-yeast once weekly (supranutritional Se-yeast), in addition to Na selenite at 0.3 mg Se/kg dry matter in their rations. Concentrations of whole-blood (WB) Se and serum Se, erythrocyte glutathione (GSH), and serum albumin, cholesterol, α-tocopherol, haptoglobin, serum amyloid A (SAA), calcium, magnesium, phosphorus, non-esterified fatty acids, and β-hydroxybutyrate were measured directly after calving, at 48 h, and 14 days of lactation in 10 cows of each group. Supranutritional Se-yeast supplementation affected indicators of antioxidant status and inflammation. Cows fed a supranutritional Se-yeast supplement during the last 8-weeks of gestation had higher Se concentrations in WB (overall 52 % higher) and serum (overall 36 % higher) at all-time points, had higher SAA concentrations at 48 h (98 % higher), had higher erythrocyte GSH (38 % higher) and serum albumin concentrations (6.6 % higher) at 14 days, and had lower serum cholesterol concentrations and higher α-tocopherol/cholesterol ratios at calving and at 48 h compared with control cows. In conclusion, feeding Se-replete cows during late gestation a supranutritional Se-yeast supplement improves antioxidant status and immune responses after calving without negatively impacting other micronutrients and energy status.     

Phosphorus feeding practices,barriers to and motivators for minimising phosphorus feeding to dairy cows in diverse dairy farming systems

Minimising phosphorus (P) feeding to dairy cows can reduce feed costs and minimise water pollution without impairing animal performance. This study aimed to determine current P feeding practices and identify the barriers to and motivators for minimising P feeding on dairy farms, using Great Britain (GB) dairy farming as an example of diverse systems. Farmers (n = 139) and feed advisers (n = 31) were involved simultaneously in independent questionnaire surveys on P feeding in dairy farms. Data on the herd size, milk yield and concentrate fed were analysed using ANOVA to investigate the effect of farm classification, region, and feed professional advice. Chi-square tests were used to investigate associations between farm characteristics and implemented P feeding and management practices. Most farmers (72%) did not know the P concentration in their lactating cow’s diet and did not commonly adopt precision P feeding practices, indicating that cows might have been offered dietary P in excess of recommended P requirement. Farmers’ tendency to feed P in excess of recommendations increased with herd size, but so did their awareness of P pollution issues and likeliness of testing manure P. However, 68% of farmers did not analyse manure P, indicating that mineral P fertiliser application rates were not adjusted accordingly, highlighting the risk of P being applied beyond crops’ requirement. Almost all farmers (96%) were willing to lower dietary P concentration but the uncertainty of P availability in feed ingredients (30%) and concerns over reduced cow fertility (22%) were primary barriers. The willingness to reduce dietary P concentrations was driven by the prospect of reducing environmental damage (28%) and feed costs (27%) and advice from their feed professionals (25%). Most farmers (70%) relied on a feed professional, and these farmers had a higher tendency to analyse their forage P. However, farmers of pasture-based systems relied less on feed professionals. Both farmers (73%) and feed advisers (68%) were unsatisfied with the amount of training on P management available. Therefore, the training on P management needs to be more available and the influence that feed professionals have over P feeding should be better utilised. Study findings demonstrate the importance of considering type of dairy farming systems when developing precision P feeding strategies and highlight the increasing importance of feed professionals in minimising P feeding.     

Prophylactic effect of a progestin (Chlormadinone acetate = CAP) on fertility of dairy cows after post-partum use

Claims made for prophylactic effects by a progestin (Chlormadione acetate = CAP) on fertility, given peroral daily to dairy cows from Day 15 to 35 post-partum, were investigated in field trials in a total of 1516 cows in Northern Germany, on 12 privately and one government-owned dairy farm, between 1969 and 1973. All animals were inseminated at estrus after Day 50 post-partum. For all treated animals, significant reduction of the calving interval by 11 days (p < 0.01) was recorded. In 942 cows, in which comparisons between treatment and control animals under identical environmental conditions were made, calving intervals were reduced by 10.5 days (p < 0.01) and the percentage of cows remaining infertile over two years was reduced from 12.4 % in the control population to 6.4 % in treated cows (p < 0.05). These advantages of CAP were most pronounced in cows older than 5 years and animals producing less than 25 kg milk/day during the first two months post-partum. In individual farms, calving intervals between treatment and control groups ranged from insignificant differences up to 44 days. Predictability of breeding dates, assurance of desirable short calving intervals and improved fertility makes this a tool for problem farms and well managed dairies alike.     

Implications of feed concentrate reduction in organic grassland-based dairy systems: a long-term on-farm study

In response to increasing efforts for reducing concentrate inputs to organic dairy production in grassland-rich areas of Europe, a long-term study was conducted, which assessed the impacts of concentrate reductions on cows’ performance, health, fertility and average herd age. In total, 42 Swiss commercial organic dairy cattle farms were monitored over 6 years (‘Y0’, 2008/09 until ‘Y5’, 2013/14). In comparison with overall data of Swiss herdbooks (including conventional and organic farms), the herds involved in the project had lower milk yields, similar milk solids, shorter calving intervals and higher average lactation numbers. During the first 3 project years farmers reduced the concentrate proportion (i.e. cereals, oilseeds and grain legumes) in the dairy cows’ diets to varying degrees. In Y0, farms fed between 0% and 6% (dietary dry matter proportion per year) of concentrates. During the course of the study they changed the quantity of concentrates to voluntarily chosen degrees. Retrospectively, farms were clustered into five farm groups: Group ‘0-conc’ (n=6 farms) already fed zero concentrates in Y0 and stayed at this level. Group ‘Dec-to0’ (n=11) reduced concentrates to 0 during the project period. Groups ‘Dec-strong’ (n=8) and ‘Dec-slight’ (n=12) decreased concentrate amounts by >50% and <50%, respectively. Group ‘Const-conc’ (n=5 farms) remained at the initial level of concentrates during the project. Milk recording data were summarised and analysed per farm and project year. Lactation number and calving intervals were obtained from the databases of the Swiss breeders’ associations. Dietary concentrate amounts and records of veterinary treatments were obtained from the obligatory farm documentations. Data were analysed with GLMs. Daily milk yields differed significantly between farm groups already in Y0, being lowest in groups 0-conc (16.0 kg) and Dec-to0 (16.7 kg), and highest in groups Dec-slight (19.6 kg) and Const-conc (19.2 kg). Milk yield decreases across the years within groups were not significant, but urea contents in milk decreased significantly during the course of the project. Milk protein, somatic cell score, fat–protein ratio, average lactation number, calving interval and frequency of veterinary treatments did not differ by group and year. In conclusion, 5 years of concentrate reduction in low-input Swiss organic dairy farms, affected neither milk composition, nor fertility and veterinary treatments. Milk yields tended to decline, but at a low rate per saved kilogram of concentrate.     

Comparison of artificial insemination and natural service cost effectiveness in dairy cattle

Reproductive efficiency in the dairy herd is the most important factor for its economic success and a major concern for dairy farmers when using artificial insemination (AI) or natural service (NS). Our objectives were to estimate, compare and analyse the costs associated with breeding cattle by do-it-yourself (DIY) AI and NS and identify the factors that influence them, under typical dairy farming conditions in Greece. A simulation study was designed based on data from 120 dairy cattle farms that differed in size (range 40 to 285 cows) and milk production level (4000 to 9300 kg per cow per year). Different scenarios were employed to estimate costs associated directly with AI and NS as well as potentially extended calving intervals (ECI) due to AI. Results showed that bull maintenance costs for NS were €1440 to €1670 per year ($1,820 to $2,111). Direct AI costs were higher than those for NS for farms with more than 30 cows and ECI constituted a considerable additional burden. In fact, amongst the factors that affected the amount of milk needed to cover total extra AI costs, number of days open was the dominant one. Semen, feed and heifer prices had a very small effect. When, hypothetically, use of NS bulls results in a calving interval of 12 months, AI daughters with a calving interval of 13.5 months have to produce about 705 kg of additional milk in order to cover the extra cost. Their actual milk production, however, exceeds this limit by more than 25%. When real calving intervals are considered (13.0 v. 13.7 months for NS and AI, respectively) AI daughters turn out to produce more than twice the additional amount of milk needed. It was concluded that even under less than average management conditions, AI is more profitable than the best NS scenario. The efficient communication of this message should be a primary concern of the AI industry.     

The use of embryo transfer in the field for increased calf crops in beef and dairy cattle

Non-surgical transfer of one embryo to 63 previously synchronized inseminated recipients was performed on farms to induce twinning in beef and dairy cattle. All the transfers were done by technicians of A.I. centers. After calving, a twinning rate of 44.4% was achieved with no differences between beef Charolais heifers (45.4%), lactating Normande cows (42.8%) and dairy Friesian cows (45.4%). Compared with controls, the calving crop after a three-breeding-cycle period was significantly higher with recipients: 1.16 calf per treated recipient vs. 0.83 calf per control animal. It would seem that the possibility of obtaining about one-third more calves with embryo transfer could be of economical interest to increase meat production from cattle herds.     

Resumption of postpartum ovarian cyclicity in high-producing Holstein cows

The objective of this study was to investigate the resumption of ovarian cyclicity postpartum in high-producing dairy cows in commercial dairy farms under subtropical conditions. The cows were kept in a free-stall or tie-stall barn. Milk samples were collected from cows twice weekly, and progesterone in the skim milk was assayed by double-antibody ELISA. Cows were examined rectally and vaginoscopically at 2-week intervals after calving. Body condition score (BCS) and body weights were taken before and after calving. A cow was considered to have resumed ovarian cyclicity on the day of ovulation if followed by regular ovarian cycles. Thirty seven percent (n=20/54) of the cows had normal resumption of ovarian cyclicity (resumption within 45 days after calving), and 63% (n=34/54) had delayed resumption (resumption did not occur until >45 days after calving). Delayed resumption Type I (one or more ovarian cycles with luteal phase >20 days, i.e. prolonged luteal phase; 31.5%) and delayed resumption Type II (first ovulation did not occur until > or =45 days after calving, i.e. delayed first ovulation; 24.1%) were the most common types of delayed resumptions. Almost half (46.3%) of the cows did not resume their ovarian cyclicity until >65 days postpartum. Cows with delayed resumption Type I had a higher incidence of abnormal cervico-vaginal discharge (64.7%) and incomplete uterine involution (94.1%) compared to cows with normal resumption (P<0.01). The BCS of cows with delayed resumption Type II were lower than those of normal resumption cows at 5 weeks and later in the postpartum period (P<0.05). Approximately two-thirds of high-producing cows had delayed resumption of ovarian cyclicity postpartum. Prolonged luteal phase and delayed first ovulation were two important ovarian dysfunctions that delayed postpartum resumption of cyclicity in high-producing dairy cows.     

Energy intake in late gestation affects blood metabolites in early lactation independently of milk production in dairy cows

The present experiment examined the effect of offering either a high- (H) or low- (L) energy-density diet in late gestation and early lactation on physiological parameters, body condition score (BCS) and milk production in early lactation. In all, 40 multiparous Holstein cows were randomly allocated to one of four treatments in a 2 × 2 factorial design, where the factors were H- or L-energy density in a total mixed ration (TMR) both pre- and post-calving. Consequently, there were four treatment groups: HH, HL, LL and LH. The pre-calving treatment was initiated 100 days prior to expected calving; the H TMR was fed ad libitum whereas the L TMR was restricted to 10 kg dry matter/day during late lactation, and to approximately 75% of energy requirements from drying off until calving. Both diets were offered ad libitum post-calving. Feeding diet H compared to L pre-calving led to higher BCS at calving (2.68 v. 2.34, P < 0.01). Energy corrected milk yield and energy-intake post-calving were not affected by pre-calving diets. Changes in BCS and blood concentrations of non-esterified fatty acids, beta-hydroxybutyrate and glucose in early lactation showed that cows offered diet H pre-calving generally mobilised more body reserves compared to cows offered diet L pre-calving. An interaction between pre- and post-calving diets showed that cows offered diet H pre-calving had lower body tissue mobilisation when offered diet H post-calving compared to diet L. Cows offered diet L pre-calving, did not mobilise differently whether they were offered diet H or L post-calving. The pre- and post-calving diets had no effect on liver triacylglycerol, whereas liver glycogen was higher in cows on treatment HH compared to the other three treatments. Collectively, these results indicate that overfeeding should be avoided in late gestation and that a high-energy-density diet is desirable in early lactation in order to obtain a more favourable metabolic profile.     

Frequency of twin births among Holstein-Friesian cows in a warm dry climate

The objectives of this study were to examine 1) the effect of parity of dam and season of birth on the incidence of twins in Holstein-Friesian cattle in a warm, dry climate and 2) the sex ratio, gestation period and birth weight of calves born. Natural calvings (n = 24,843) from nine dairy farms in Saudi Arabia were evaluated over an 8-year period. The calendar year was divided into six bimonthly intervals to identify a possible seasonal effect on the number of natural twins born (twinning rate). The twinning rate increased (P < 0.05) from 1.0% (103 10,094 ) at first calving to 8.0% (1,178 14,749 ) for all the subsequent calvings. The twinning rate was similar with the second calving (P(2)) at 7.0% (417 5,929 ), the third calving (P(3)) at 7.5% (218 2,896 ), and the fourth calving (P(4)) at 7.8% (147 1,864 ). Correspondingly, cows having >/= five calves had a higher (P < 0.01) twinning rate at 9.0% (164 1,805 ) than cows with too, three or four calvings collectively at 7.3% (782 10,689 ). The seasonal effect on twinning rate was significant within all parity calvings except in primiparous females. The peak twinning rate occurred in the third season interval (May/June) at 9.3% (66 708 ) with P(2), at 13.0% (34 262 ) with P(3), at 13.8% (27 196 ) with P(4), and at 12.5% (23 184 ) with P(5) females. The male to female ratio was different (P < 0.01) for multiparous females (55:46; n = 12,305). The ratio of males to females (55:45) was also different (P < 0.01) for all twin pairs (n = 1,151), evaluated in the study. The gestation period for cows with single calves was 8.5 days longer (P < 0.05) than that of cows carrying twin calves. The birth weight of single calves was 13.1 kg greater (P < 0.05) than that of twin calves. The reason for the marked increase in the twinning rate during the warmest months may be explained by greater embryo mortality in the hot vs cool months.     

Relationships between transition period diet,metabolic parameters and fertility in lactating dairy cows

Cows in severe negative energy balance after calving have reduced fertility, mediated by metabolic signals influencing the reproductive system. We hypothesised that transition diet could alter metabolic status after calving, and thus influence fertility. Multiparous dairy cows were assigned to four transition groups 6 weeks pre-calving and fed: (a) basal control diet (n = 10); (b) basal diet plus barley (STARCH, n = 10); (c) basal diet plus Soypass (high protein, HiPROT, n = 11); or (d) no transition management (NoTRANS, n = 9). All cows received the same lactational diet. Blood samples, body weights and condition scores (BCS) were collected weekly. Fertility parameters were monitored using milk progesterone profiles and were not affected by transition diet. Data from all cows were then combined and analysed according to the pattern of post-partum ovarian activity. Cows with low progesterone profiles had significantly lower insulin-like growth factor-I (IGF-I) and insulin concentrations accompanied by reduced dry matter intakes (DMIs), BCS and body weight. Cows with prolonged luteal activity (PLA) were older and tended to have lower IGF-I. Analysis based on the calving to conception interval revealed that cows which failed to conceive (9/40) also had reduced IGF-I, BCS and body weight. Fertility was, therefore, decreased in cows which were in poor metabolic status following calving. This was reflected in reduced circulating IGF-I concentrations and compromised both ovarian activity and conception. There was little effect of the transition diets on these parameters.     

Questionnaire identifying management practices surrounding calving on spring-calving dairy farms and their associations with herd size and herd expansion

Healthy calves are fundamental to any profitable dairy enterprise. Research to-date, has focused on year-round calving systems which experience many different challenges compared to spring-calving systems. The objective of the present study was to determine the on-farm dry cow, calving, and colostrum management practices of spring-calving dairy production systems, and quantify their associations with herd size and herd expansion status (i.e. expanding or not expanding). Information on these management practices was available from a survey of 262 Irish spring-calving dairy farmers, representative of the Irish national population. Herd expansion in the 2 years before, and the year that the survey was conducted was not associated with any of the management practices investigated. Fifty-three percent of respondents had an average calving season length of 10 to14 weeks with 35% of herds having a longer calving season. Previous research in cattle has documented that both colostrum source and feeding management are associated with the transmission of infectious disease from cow to calf. In the present study 60% of respondents fed calves colostrum from their own dam; however, 66% of those respondents allowed the calf to suckle the dam, 23% of survey respondents fed calves pooled colostrum. Larger herds were more likely (P<0.01) to use pooled colostrum supplies, while smaller herds were more likely (P<0.05) to allow the calf to suckle the dam. The majority (86%) of respondents had stored supplies of colostrum; average-sized herds had the greatest likelihood of storing colostrum (P<0.05), compared to other herd sizes; larger sized herds had a lesser likelihood (P<0.05) of storing colostrum in a freezer, compared to other herd sizes. Although freezing colostrum was the most common method used to store colostrum (54% of respondents), 17% of respondents stored colostrum at room temperature, 29% of which stored it at room temperature for greater than 4 days. The results from the present study indicate that a particular focus needs to be placed on calving and colostrum management because this study has highlighted a number of areas which are below international standards, and may have repercussions for calf health. Furthermore, management practices on larger farms could be improved and, as these represent the future of dairy farming, a focus needs to be placed on them. Expanding herds are not a particular concern as herd expansion, independent of herd size, does not seem to be associated with calving and colostrum management practices on Irish spring-calving dairy herds.     

Circulating PgF2alpha and nutritional parameters at parturition in dairy cows with and without retained placenta: Relation to prepartum diet

Reproductive and biochemical parameters were studied at parturition in multiparous single-carrying Holstein cows. These were compared in animals with (n=14) and without (n=40) a retained placenta and then according to 2 prepartum diets (corn silage/concentrate, n=44; grass silage/concentrate, n=10) in cows with and without retained placentas. Cows with retained placentas had a 4-day shorter gestation period and gave birth to 5 kg-lighter calves than cows without retained placentas. Furthermore, their plasma PGFM -PgF2alpha main metabolite- (3325 vs 5675 pg/ml; P<0.01) and glucose (79.2 vs 95.2 mg/100ml; P<0.05) levels were lower and their protein concentration was higher (85.7 vs 76.5 g/l; P<0.05) than those of cows without retained placentas. Retained placenta incidence in cows fed grass-silage was higher than in cows fed corn-silage (60% vs 18.2%; P<0.05). Cows with retained placentas and fed corn silage had shorter gestation lengths, gave birth to lighter calves, and had less circulating glucose at calving (77.6 vs 96.5 mg/100ml; P<0.05) than cows without retained placentas and fed the same forage. Cows with retained placentas and fed grass silage had less PGFM (2172 vs 4530 pg/ml; P<0.05) than cows without retained placentas and fed the same forage. Calving number, sex ratio and preceeding milk yield were not different between the two groups of cows whatever their prepartum diet. In the dairy cow, retained placenta could be due to a PgF2alpha or an energy deficiency at calving. Roles of the dietary polyunsaturated fatty acids toward the Pg synthesis and of the energy supply before calving in relation to retained placenta are discussed here.