Calving traits, milk production, body condition, fertility, and survival of Holstein-Friesian and Norwegian Red dairy cattle on commercial dairy farms over 5 lactations.

The objective of this study was to compare calving traits, BCS, milk production, fertility, and survival of Holstein-Friesian (HF) and Norwegian Red (NR) dairy cattle in moderate-concentrate input systems. The experiment was conducted on 19 commercial Northern Ireland dairy farms, and involved 221 HF cows and 221 NR cows. Cows completed 5 lactations during the experiment, unless they died or were culled or sold. Norwegian Red cows had a lower calving difficulty score than HF cows when calving for the first and second time, but not for the third and fourth time. At first calving, the incidence of stillbirths for NR cows was 4%, compared with 13% for HF cows, whereas no difference existed between breeds in the proportion of calves born alive when calving for the second time. When calving for the first time, NR cows had a poorer milking temperament than HF cows, whereas milking temperament was unaffected by breed following the second calving. Holstein-Friesian cows had a higher full-lactation milk yield than NR cows, whereas NR cows produced milk with a higher milk fat and protein content. Full-lactation fat + protein yield was unaffected by genotype. Norwegian Red cows had a lower somatic cell score than HF cows during all lactations. Although NR cattle had a higher BCS than the HF cows during lactations 1 and 2, no evidence existed that the 2 genotypes either lost or gained body condition at different rates. Conception rates to first artificial insemination were higher with the NR cows during lactations 1 to 4 (57.8 vs. 40.9%, respectively), with 28.5% of HF cows and 11.8% of NR cows culled as infertile before lactation 6. A greater percentage of NR cows calved for a sixth time compared with HF cows (27.2 vs. 16.3%, respectively). In general, NR cows outperformed HF cows in traits that have been historically included in the NR breeding program.

An evaluation of the effect of altering nutrition and nutritional strategies in early lactation on reproductive performance and estrous behavior of high-yielding Holstein-Friesian dairy cows.

Reproductive performance in the high-yielding dairy cow has severely decreased in the last 40 yr. The aim of this study was to compare the effectiveness of 4 nutritional strategies in improving the reproductive performance of high-yielding dairy cows. It was hypothesized that offering cows a high-starch ration in early lactation would enhance the onset of luteal activity, and that decreasing the severity of negative energy balance in the early postcalving period would improve reproductive parameters. Nutritional regimens aimed at improving fertility were applied to 96 Holstein-Friesian dairy animals. Upon calving, animals were allocated in a balanced manner to one of 4 dietary treatments. Primiparous animals were balanced according to live weight, body condition score and calving date. Multiparous animals were balanced according to parity, previous lactation milk yield, liveweight, body condition score and calving date. Treatment 1 was based on an industry best practice diet (control) to contain 170 g of crude protein/kg of dry matter. Treatment 2 was an individual cow feeding strategy, whereby the energy balance (EB) of individual animals was managed so as to achieve a predetermined target daily EB profile (±10 MJ/d). Treatment 3 was a high-starch/high-fat combination treatment, whereby an insulinogenic (high-starch) diet was offered in early lactation to encourage cyclicity and followed by a lipogenic (low-starch, high-fat) diet to promote embryo development. Treatment 4 was a low-protein diet, containing 140 g of crude protein/kg of dry matter, supplemented with protected methionine at an inclusion level of 40 g per animal per day. The nutritional strategies implemented in this study had no statistically significant effects on cow fertility measures, which included the onset of luteal activity, conception rate, in-calf rate, and the incidence of atypical cycles. The individual cow feeding strategy improved EB in early lactation but had no benefit on conception rate to first insemination. However, conception rate to second insemination, 100-d pregnancy rate (from the commencement of breeding), and overall pregnancy rate tended to be higher in this group. The high-starch/high-fat treatment tended to decrease the proportion of delayed ovulations and increase the proportion of animals cycling by d 50 postcalving. Animals that failed to conceive to first insemination had a significantly longer luteal phase in the first cycle postpartum and a longer inter-ovulatory interval in the second cycle postpartum. With regards to estrous behavior, results indicate that as the size of the sexually active group increased, the intensity of estrus and the expression of mounting or attempting to mount another cow also increased. Furthermore, cows that became pregnant displayed more intense estrous behavior than cows that failed to become pregnant.

Effect of precalving and postcalving dietary energy level on performance and blood metabolite concentrations of dairy cows throughout lactation.

The effects of the level of energy intake (high E and low E) offered before and after calving on body condition score at calving, production performance, and energy status in the first 250 d of lactation were evaluated in a 2 × 2 factorial design experiment involving 80 Holstein-Friesian dairy animals (40 primiparous and 40 multiparous). From d 80 until d 21 precalving, primiparous animals were offered either high or low pasture allowances. Thereafter, these animals were housed and had ad libitum access to a high energy density diet (high E) or restricted access [6 kg of dry matter (DM) per d] to a low energy density diet (low E), respectively, until calving. From d 100 until d 42 precalving, multiparous animals were offered either ad libitum or restricted (10 kg of DM/d) access to a late lactation diet, and thereafter, had ad libitum access to a high E diet or restricted access (7 kg of DM complete diet/d) to a low E diet, respectively, until calving. The forage to concentrate (F:C) ratios (DM basis) of these high E and low E diets [d 42 (d 21 in primiparous animals) until calving] were 64:36 and 83:17, respectively. Cows offered high E and low E precalving diets were allocated to either a high E or low E postcalving diet [F:C ratio (DM basis) of 30:70 and 70:30, respectively] and remained on these diets until d 250 of lactation. Multiparous animals offered a high E diet precalving had a significantly higher body condition score at calving than those offered the low E diet precalving. This effect was not evident in primiparous animals. Precalving diet had no significant effect on plasma nonesterified fatty acid concentrations during the last 3 wk precalving in primi- or multiparous animals. Primiparous animals offered a high E diet precalving had significantly higher postcalving plasma concentrations of nonesterified fatty acid, suggesting greater mobilization of body reserves. Primi- and multiparous animals offered a high E diet postcalving had a significantly higher dry matter intake, milk yield, and energy status postcalving compared with animals offered a low E diet postcalving. Milk yields of primiparous animals offered high E and low E diets postcalving were 29.7 and 24.8 kg/d, respectively, and milk yield of multiparous animals offered high E and low E diets postcalving were 33.5 and 28.2 kg/d, respectively. It is concluded that altering body condition score during the dry period is difficult but that specific dietary regimens applied precalving can have a significant influence on postcalving production and energy-related parameters.

Mitigation of enteric methane emissions through improving efficiency of energy utilization and productivity in lactating dairy cows.

The data set used in the present study was obtained from 20 energy metabolism studies involving 579 lactating dairy cows (511 Holstein-Friesian, 36 Norwegian Red, and 32 Jersey-Holstein crossbreds) varying in genetic merit, lactation number, stage of lactation, and live weight. These cows were offered diets based on grass silage (n=550) or fresh grass (n=29), and their energy intake and outputs, including methane energy (CH(4)-E), were measured in indirect open-circuit respiration calorimeter chambers. The objective was to use these data to evaluate relationships between CH(4)-E output and a range of factors in animal production and energetic efficiency in lactating dairy cows under normal feeding regimens. The CH(4)-E as a proportion of milk energy output (E(l)), E(l) adjusted to zero energy balance (E(l(0))), or intakes of gross energy (GE), digestible energy (DE), or metabolizable energy (ME) was significantly related to a wide range of variables associated with milk production (E(l) and E(l(0))) and energy parameters (energy intake, metabolizability, partitioning, and utilization efficiencies). Three sets of linear relationships were developed with experimental effects removed. The CH(4)-E/GE intake (r(2)=0.50-0.62) and CH(4)-E/E(l) (r(2)=0.41-0.68) were reduced with increasing feeding level, E(l)/metabolic body weight (MBW; kg(0.75)), E(l(0))/MBW, GE intake/MBW, DE intake/MBW, and ME intake/MBW. Increasing dietary ME/DE decreased CH(4)-E/E(l) (r(2)=0.46) and CH(4)-E/GE intake (r(2)=0.72). Dietary ME concentration and ME/GE were also negatively related to CH(4)-E/GE intake (r(2)=0.47). However, increasing heat production/ME intake increased CH(4)-E as a proportion of E(l) (r(2)=0.41), E(l(0)) (r(2)=0.67) and energy intake (GE, DE, and ME; r(2)=0.62 and 0.70). These proportional CH(4)-E variables were reduced with increasing ratios of E(l)/ME intake and E(l(0))/ME intake and efficiency of ME use for lactation (r(2)=0.49-0.70). Fitting CH(4)-E/E(l) or CH(4)-E/E(l(0)) against these energetic efficiencies in quadratic rather than linear relationships significantly increased r(2) values (0.49-0.67 vs. 0.59-0.87). In conclusion, CH(4)-E as a proportion of energy intake (GE, DE, and ME) and milk production (E(l) and E(l(0))) can be reduced by increasing milk yield and energetic efficiency of milk production or by reducing energy expenditure for maintenance. The selection of dairy cows with high energy utilization efficiencies and milk productivity offers an effective approach to reducing enteric CH(4) emission rates.

Effect of offering dairy cows diets differing in phosphorus concentration over four successive lactations: 1. Food intake, milk production, tissue changes and blood metabolites.

The loss of phosphates from dairy farms contributes to the eutrophication of waterways. Whilst reducing the phosphorus (P) content of dairy cow diets has the potential to help reduce phosphate losses, diets containing inadequate dietary P may have a negative effect on cow health and performance. To address this issue, 100 winter-calving Holstein-Friesian dairy cows were offered diets containing either 'high' or 'low' levels of dietary P. The experiment was conducted over a 4-year period, with 80 primiparous cows commencing the study in year 1, while a further 20 primiparous cows commenced the study in year 2. Rations offered during the winter comprised grass silage, maize silage (70 : 30 dry matter (DM) basis, approximately) and concentrates (10.0 to 12.0 kg/cow per day). During the summer periods in years 1 and 2, half of the cows grazed both day and night, while the remaining cows grazed by day, and were housed by night and offered grass silage. During years 3 and 4, all cows grazed both day and night during the summer period. Concentrate feed levels during the summer periods were 3.0 to 4.0 kg/cow per day. Different dietary P levels were achieved by offering concentrates containing either high or low P levels during the winter period (approximately 7.0 or 4.4 g P/kg DM respectively), and during the summer period (approximately 6.8 or 3.6 g P/kg DM, respectively). Total ration P levels averaged 4.9 and 3.6 g P/kg DM for the 'high' and 'low' P winter diets respectively, and 4.2 and 3.6 g P/kg DM for the 'high' and 'low' P summer diets respectively. A total of 95, 70, 50 and 22 cows completed each of lactations 1 to 4 respectively. Dietary P level had no significant effect on food intake, milk output or milk composition (P > 0.05). Plasma P concentrations were significantly lower with cows offered the 'low' P diet in each of lactations 1 to 4 (P < 0.05). In each of lactations 3 and 4, cows offered the 'low' P diet tended to have lower condition scores and live weights than those offered the 'high' P diet. The results of this experiment highlight that the P content of dairy cow diets can be substantially reduced with no detrimental effect on dairy cow performance.

Effect of offering dairy cows diets differing in phosphorus concentration over four successive lactations: 2. Health, fertility, bone phosphorus reserves and nutrient utilisation.

This experiment examined the long-term effects of offering diets containing low levels of dietary phosphorus (P) on dairy cow health, fertility and bone composition, and the effect of dietary P level on nutrient utilisation. One hundred winter-calving Holstein-Friesian dairy cows were offered diets containing either 'high' or 'low' levels of dietary P over a 4-year period. Rations offered during the winter included grass silage, maize silage (70 : 30 dry matter (DM) basis, approximately) and concentrates (10.0 to 12.0 kg/cow per day). During the summer periods in years 1 and 2, half of the cows grazed both day and night, while the remaining cows grazed by day, and were housed by night and offered grass silage. During years 3 and 4, all cows grazed both day and night during the summer period. Concentrate feed levels during the summer periods were 3.0 to 4.0 kg/cow per day. Different dietary P levels were achieved by offering concentrates containing either high or low P levels during the winter period (approximately 7.0 or 4.4 g P/kg DM, respectively) and during the summer period (approximately 6.8 or 3.6 g P/kg DM, respectively). Total ration P levels averaged 4.9 and 3.6 g P/kg DM for the high and low P winter diets, respectively, and 4.2 and 3.6 g P/kg DM for the high and low P summer diets, respectively. A total of 95, 70, 50 and 22 cows completed each of lactations from 1 to 4, respectively. Neither the incidence of lameness or mastitis, or milk somatic cell count, were affected by dietary P level (P > 0.05), while none of the fertility parameters recorded in any of lactations from 1 to 4 was affected by the dietary P level (P > 0.05). Dietary P level had no effect on the specific gravity, ash or calcium content of rib cortical bone cores (n = 78 cows), while the P content of cortical bone (g/kg fresh, g/kg DM and mg/ml fresh bone) was lower with cows offered low P diets (P < 0.05). Dietary P level had no significant effect on the digestibility of either the DM, nitrogen, energy or acid detergent fibre fraction of the diet (P > 0.05), while faecal P excretions were reduced by a mean of 27 g/cow per day with cows offered the low P diets during the winter period. The results of this study indicate that dietary P levels can be reduced to proportionately 0.8 (approximately) of current UK feeding standards (Agricultural and Food Research Council, 1991), with no detrimental effect on dairy cow health or fertility, while having only minor effects on bone composition.

Effect of dietary protein content on the fertility of dairy cows during early and mid lactation.

Ninety autumn-calving Holstein dairy cows (45 primiparous and 45 multiparous; mean parity, 3.1) were allocated to 1 of 3 treatments; 173, 144, or 114 g of crude protein (CP)/kg of dry matter (DM) from calving until d 150 of lactation. On d 151 of lactation, half the animals receiving 114 g of CP/kg of DM went onto 144 g of CP/kg of DM, half of the animals receiving 144 g of CP/kg of DM went onto 173 g of CP/kg of DM, and half of the animals receiving 173 g of CP/kg of DM went onto 144 g of CP/kg of DM, with the remaining animals staying on their original treatments. This resulted in 6 treatments in mid to late lactation: 114/114; 144/144; 173/173; 114/144; 144/173; and 173/144 g of CP/kg of DM. Overall, 95.3% of cows intended for breeding conceived during a 6-mo breeding period. The average pregnancy rates to first service and first plus second service were 30.9% [standard error of the difference (SED), 0.05] and 56.7% (SED, 0.05) respectively. The average 100 d in-calf rate from the start of the breeding period was 70.5%, and at least one abnormal progesterone profile was observed in 62% of animals. An increase in dietary protein content decreased the requirement for treatment of metritis. There was no effect of dietary protein content on any of the reproductive or progesterone measures; for example, days to conception, calving interval, 100 d in-calf rate (from commencement of breeding), days to onset of luteal activity, average luteal phase, average interovulatory interval, or average interluteal interval. An increase in dietary protein content decreased the average daily energy balance. A more positive energy balance was associated with an increased requirement for the treatment of metritis in the current study. Cumulative energy balance was positively associated with conception. There was no effect of the concentration of plasma urea on any of the reproductive variables; however, the concentration of serum leptin was favorably associated with the time to progesterone increase above 3 ng/mL, which has been deemed essential for embryo survival. Additionally, the average peak concentration of progesterone and the duration of the average luteal phase were favorably associated with the interval from calving to conception. The latter relationships emphasize the importance of progesterone in achieving and maintaining pregnancy.

Effect of dietary protein content on animal production and blood metabolites of dairy cows during lactation.

Ninety autumn-calving Holstein dairy cows [45 primiparous and 45 multiparous (mean parity, 3.1)] were allocated to 1 of 3 dietary crude protein (CP) concentrations: 173, 144, or 114 g of CP/kg of DM, from calving until d 150 of lactation. On d 151, half of the animals in each treatment were allocated an alternative dietary protein concentration. Half of the animals receiving 114 g of CP/kg of DM went onto 144 g of CP/kg of DM; half of the animals receiving 144 g of CP/kg of DM went onto 173 g of CP/kg of DM; and half of the animals receiving 173 g of CP/kg of DM went onto 144 g of CP/kg of DM, with the remaining animals staying on their original treatment. This resulted in 6 treatments in the mid to late lactation period: 114/114, 144/144, 173/173, 114/144, 144/173, and 173/144 g of CP/kg of DM. An increase in dietary CP concentration significantly increased milk, fat, and protein yield in early lactation (d 1 to 150). Dry matter intake was also increased with increased dietary protein concentration; however, this was not significant between 144 and 173 g of CP/kg of DM. Increased dietary CP significantly increased plasma urea, albumin, and total protein concentrations but had no significant effect on NEFA, leptin, or IGF-1 concentrations. Decreasing the dietary CP concentration in mid-late lactation (d 151 to 305) from 173 to 144 g/kg of DM had no significant effect on milk yield, dry matter intake, or milk fat and protein yield, compared with animals that remained on 173 g of CP/kg of DM throughout lactation. Increasing dietary CP concentration from 144 to 173 g/kg of DM significantly increased dry matter intake compared with animals that remained on the 144 g of CP/kg of DM throughout lactation. There were no significant dietary treatment effects on live weight or body condition score change throughout the experiment. Results of this study indicate that high protein diets (up to 173 g of CP/kg of DM) improved feed intake and animal performance in early lactation (up to d 150), but thereafter, protein concentration can be reduced to 144 g of CP/kg of DM with no detrimental effects on animal performance.

Effect of dietary protein content on estrous behavior of dairy cows during early and mid lactation.

One of the main contributing factors to the decline in fertility in contemporary dairy farming is the inability to detect cows in estrus. In the current study, 90 Holstein dairy cows [45 primiparous and 45 multiparous (mean parity of 3.1)] were allocated to 1 of 3 treatments at calving; 173, 144, or 114 g of crude protein/kg of dry matter. Estrous behavior was recorded for one 30-min period every 12 h from calving until all animals reached 140 d postpartum. Behavioral activities were recorded according to a scoring system developed by Van Eerdenburg et al. (1996), with 9 key estrous behavioral activities each allocated a given number of points. If the total score allocated was greater than or equal to 50 points during a single or consecutive observational periods, then the animal was deemed to be in estrus. A total of 238 estrous cycles scored 50 points or above on the Van Eerdenburg et al. (1996) scale in this experiment, with 51.7% of these cycles being characterized as standing immobile on mounting. There were no direct effects of dietary protein content on estrous behavior; however, 3 significant stage of lactation x protein treatment interactions occurred for the behavioral activities (mucous discharge, chin resting, and mounting the head side of another cow), but no consistent trends were apparent from the predicted means. There was a significant influence of parity on the frequency of mounting the head side of another cow and total number of behavior activities displayed per estrous cycle. In both cases multiparous animals displayed fewer behavioral activities than primiparous animals. An increase in the size of the sexually active group (animals in estrus at the same time, up to 5) significantly increased the expression of mounting or attempting to mount another cow, the number of cycles in which standing immobile on being mounted was observed, the total estrous score and the proportion of cyclic animals that were diagnosed as being in estrus. The most frequent behavioral activity displayed was chin resting (89.5% of cycles), and the most reliable behavior was standing immobile on mounting (when expressed 96.4% of cows were in estrus). The most dependable (function of reliability and frequency displayed) sign of estrus was mounting or attempting to mount another cow. This behavior was expressed in 83% of cycles, and when expressed, 89% of animals were in estrus.

Beef production potential of Norwegian Red and Holstein-Friesian bulls slaughtered at two ages.

There is a paucity of data on the beef production potential of Norwegian Red (NOR) compared with 'modern' Holstein-Friesian (HF) cattle. The present study used a total of 64 bulls in a 2 × 2 factorial design study encompassing two breeds (HF and NOR) and two slaughter ages (485; E, and 610; L, days). The mean initial age and live weight of the HF bulls were 179 (s.d. 47.1) days and 203 (s.d. 64.0) kg, while the corresponding data for the NOR bulls were 176 (s.d. 39.7) days and 185 (s.d. 63.6) kg, respectively. Bulls were offered a 50 : 50 mixture (dry matter (DM) basis) of grass silage and concentrates. No breed × slaughter group interactions were recorded for any parameters evaluated (P > 0.05). HF bulls had higher (P < 0.001) DM intake and poorer (P < 0.01) efficiency of conversion of food to carcass gain than NOR bulls. HF bulls tended (P = 0.07) to have a higher rate of live-weight gain and were heavier (P < 0.001) at slaughter than NOR bulls, though both carcass weight and rate of carcass gain did not differ between the breeds (P > 0.05). NOR bulls had higher (P < 0.001) dressing proportion and carcass conformation score than HF bulls, while breed of bull had no influence (P > 0.05) on carcass fat classification, depth of subcutaneous fat, marbling score or on the weight of fat in the internal depots. Daily food intakes did not differ (P > 0.05) across the two slaughter age groups, though efficiency of conversion of food to carcass gain was poorer (P < 0.05) in the L compared with E bulls. Rate of live-weight gain was lower (P < 0.01) for L bulls, although rate of carcass gain did not differ (P > 0.05) between the E and L bulls. Increasing age at slaughter increased (P < 0.01 or greater) dressing proportion, carcass fat class, depth of subcutaneous fat, marbling score and internal fat depots, but had no effect (P > 0.05) on the carcass conformation score. Instrumental measures of meat quality indicated that meat from NOR bulls was tougher (P < 0.01) than meat from HF bulls, while delaying slaughter increased (P < 0.001) a* and C*ab, and decreased (P < 0.01) h0, indicating improved redness. It is concluded that NOR bulls have higher food efficiency and produce more highly conformed carcasses than HF bulls, but HF bulls produce more tender meat.

Relationships between urea dilution measurements and body weight and composition of lactating dairy cows.

The objective of the present study was to investigate the potential of the urea dilution technique, coupled with live animal measures to predict the body components of dairy cattle. The study involved 104 lactating Holstein-Friesian cows offered grass silage-based diets. Urea space volume (USV) was calculated from 2 collection periods of blood samples following infusion of urea at 12 (USV12, kg) and 30 (USV30, kg) min after infusion, and then as a proportion of live weight (LW) or empty body weight (EBW). All cows were slaughtered within 2 d of the USV trials. Large ranges existed in EBW and empty body concentrations of water, crude protein (CP), lipid, ash, and gross energy (GE). The USV12 and USV30 were both positively related to LW, EBW, and empty body component weights. The r2 values for USV12 were greater than USV30. The r2 values in the relationships of EBW and empty body composition with USV, however, were smaller than those with LW. Nevertheless, the relationships were improved when both USV and LW were used as predictors, rather than using either alone. Adding milk yield and body condition score as supporting predictors to prediction equations using USV and LW data for EBW, lipid, and GE contents further improved the relationships (r2 = 0.93, 0.66, and 0.77, respectively). Internal evaluation of one-third of the present data using equations developed from two-thirds of the present data indicated that using USV, live weight, and other live animal variables as predictors, rather than using USV alone, considerably improved the prediction accuracy. It was concluded that USV can be used to predict body composition, but the relationships with USV were poorer than those with LW. The USV can only be used as a supporting variable to live weight for prediction of body components in lactating dairy cows.