H. Wiktorsson

Urea concentrations in milk and blood as influenced by feeding varying amounts of protein and energy to dairy cows

Eight multiparous cows of the Swedish Red and White Breed were used to study the effect of diet on concentrations of urea in milk and plasma as well as on glucose concentrations in plasma. The cows were divided into four pairs and fed a ration containing varying amounts (low = L; standard = S; high = H) of crude protein (P) and metabolizable energy (E). When fed according to the Swedish standard (PSES), all cows had a milk urea content around 5 mmol l−1. Concentrations altered only slightly when the amount of protein ingested was decreased or increased - as long as the ratio between protein and energy was held constant (PLEL; PHEH). When the ratio was changed, however, the milk urea concentrations either decreased to around 4 mmol l−1 (PSEH; PLES) or increased to between 6.5 and 7.6 mmol l−1 (PSEL; PHEL; PHES). It was found that the main factor influencing the milk urea content was not the amount of protein ingested in relation to requirements, but the relationship between protein and energy in the ration. Concentrations of urea in morning and afternoon milk were similar and the day-to-day variations were small. The correlation between urea concentrations in plasma and milk was 0.98, with concentrations in plasma always slightly higher. Diet had no effect on blood plasma glucose concentrations.

Urea concentrations in milk in relation to milk yield, live weight, lactation number and amount and composition of feed given to dairy cows

The influences of ration composition (protein/energy ratio and crude protein as a percentage of dry matter), milk yield, live weight and parity on milk urea concentrations were studied in 13 first-calvers and 36 multiparous cows of the Swedish Red and White breed. Daily milk yields were between 4 and 28 kg and the live weights varied from 447 to 700 kg. When the cows were fed in accordance with the Swedish standard recommendations, milk urea concentrations were affected by all factors studied (P 0.05). It was concluded that the effect of milk yield seen when feed was given in accordance with the standard recommendations was not due to yield as such or to the absolute amounts of feed ingested, but to the correlation between yield and protein/energy ratio in the diet under controlled feeding conditions.

Effect of age of calf on suckling behaviour and other behavioural activities of Zebu and crossbred calves during restricted suckling periods

The objective of this study was to investigate the effect of age of calf on the behaviour of Zebu and crossbred calves during restricted suckling (RS) periods. The behaviours of 20 Zebu and 16 crossbred calves were recorded during two 30-min sessions each day after milking when the calves and their dams were brought together in a group for suckling. This was made for a time period of 2 weeks/month for 6 months postpartum.The total suckling duration was significantly longer in Zebu calves (11.8+/-0.19 min) compared to the crossbred calves (9.4+/-0.19 min), but decreased significantly in both breeds with increasing age from 1 to 6 months. The number of suckling bouts decreased from a mean of 3.8 at 1 month of age to 1.1 at 6 month (P<0.05). The duration of each suckling bout decreased significantly from a mean of 3.5+/-0.15 min at 1 month of age to 1.6+/-0.01 min at 6 months (<0.05). The frequency of crossbred calves cross-suckling (3.7%) was significantly higher than that of the Zebu calves (1.9%; P<0.05). The frequency of calves cross-suckling decreased significantly from 4.2% at 1 month of age to 2.3% at 6 months. The duration and number of bouts of cross-suckling was significantly higher in the crossbred calves (duration 0.9+/-0.06 min; bouts 3, 7) than in the Zebu calves (duration 0.5+/-0.06 min; bouts 2, 7) and decreased with increasing age of calf. The duration and number of bouts of inter-sucking was significantly higher in the crossbred calves (duration 0.6+/-0.07 min; bouts 1, 6) than in the Zebu calves (duration 0.1+/-0.04 min; bouts 0, 5) and decreased with increasing age of calf. Exploration increased in duration as the calves increased in age from 1 to 6 months (P<0.05). The duration of play increased significantly with the increase in age of calf from 1 to 6 months, and occurred mainly after nursing.

Optimising lactation cycles for the high-yielding dairy cow. A European perspective

Abstract Few investigations have been performed where effects of a planned increase of the calving interval have been elucidated. In order to study these matters, a research project has started at the Swedish University of Agricultural Sciences (SLU). The study involves researchers both at the Agricultural and Veterinary Faculties at SLU as well as from the dairy industry in Sweden. Experiments are being performed within two experimental herds (approximately 150 cows) belonging to SLU. We are now in the middle of a three-year study comparing 12- and 15-month calving intervals (herd 1) or 12- and 18-month calving intervals (herd 2). In herd 2, two milking frequencies (2 vs. 3 per day) are combined with the two calving intervals. Long-term effects on health, reproduction, milk production (including milk quality) and production efficiency are studied in detail. The plan is to study individual cows in three consecutive years. Interactions with management system and breed will also be investigated. Results from the first lactation show no significant differences in fertility between treatments. So far, milking three times per day has not given a more persistent lactation compared with milking two times a day. Some cases of salty taste of milk have been noticed.

Use of regular milking records versus daily records for nutrition and other kinds of management

Abstract Regular monthly milking record is mainly used as a tool for breeding, but is also used for nutrition and management decisions. Since the type of records have different purposes, it can be questioned if monthly regular records are optimal for nutrition and management decisions on herd level. The most optimal registration frequency is at every milking, but this is only justifiable for traits that can be measured by automatic in-line methods. Daily recording of milk yield is the trait that gives the most benefits to the farmers. The total energy requirement is to the most part dependent of the milk yield. The milk yield has the largest day-to-day variation of traits used for calculating the energy requirements and the lactation curve of milk yield varies between the cows. Systematic decline in milk yield gives a warning of disturbances in the milk production, which can be used as a tool for early warning, management decisions and predicting production capacity. In order to determine the limits for alarms, daily record for management decision requires knowledge about the day-to-day variation for the parameters. Traits with high relative day-to-day variation (milk yield, fat content and milk urea) should be recorded frequent when used for management decisions and for diagnostic purposes. Traits with low relative day-to-day variation (protein and lactose content) could be recorded less frequent. Fast and reliable cow-side methods for health and metabolic disturbances traits would be of great benefits in the future. Automatic in-line quarter milk yield units might be an excellent tool for early warning of mastitis. In conclusion daily or more frequently record for nutrition and management decision is recommended, specially for traits that can be measured automatically and has large variations between milking and during the lactation period. Automatic in-line methods for milk composition can in the future be a valuable tool for early warnings of metabolic disturbances, especially the fat content and fatty acid composition can give early warnings of feeding strategy.

Effects of drinking water flow rates and social rank on performance and drinking behaviour of tied-up dairy cows

The effect of three different water flow rates into the water-bowls (2, 7 and 12 l/min) on water intake, drinking behaviour, feed consumption, milk yield, live weight and physiological parameters was studied in two experiments, with 9 and 12 tied-up dairy cows respectively of the Swedish Red and White Breed. In the first experiment (1 C) each cow had its own water-bowl, while in the second experiment (2 C) two cows shared the same water-bowl. The dominant cow within each pair was determined (2 C). The higher flow rates led to a significant (P < 0.05) increase in water intake in both experiments. Daily drinking frequency was highest (P < 0.01) at the lowest flow rate (40 vs 28 and 30). Time per drinking was also longest (P < 0.01) for 2 l/min, while the two other flow rates did not differ significantly. Amounts of water consumed per drinking were 2.4, 3.5 and 3.4 l (NS). No significant effects of treatment on feed consumption, milk yield, live weight or physiological parameters could be detected. Dominant cows consumed significantly more water and hay than the submissive cows. Milk yield was also significantly higher for the dominant cows, 21.3 versus 20.2 kg 4% fat-corrected milk (P < 0.05).

Long-term feeding of rapeseed meal and full-fat rapeseed of double low cultivars to dairy cows

Long-term effects on dairy cow performances of feeding different levels of rapeseed meal and heattreated and crushed full-fate rapeseed, both of double low cultivars, were studied. The study included the first three lactations of 85 dairy cows. Even at the highest inclusion levels of rapeseed products, 2.5 kg DM rapeseed meal plus 0.9 kg DM full-fat rapeseed per day, there were no negative effects on animal health, feed intake, feed conversion, milk production and milk composition. Compared with other protein and fat supplements, i.e. soybean meal, cotton seed meal and tallow, the milk protein content and production tended to increase (P<0.10), while milk urea content decreased (P<0.05). Medium (1.2–1.4 kg DM) as well as high levels of rapeseed products resulted in a significant increase in thiocyanate content but a decrease in iodine content of the milk. However, milk from the rapeseedfed cows did not cause any metabolic disturbances when fed to rats. Milk fatty acid composition was affected by the inclusion of full-fat rapeseed, whereby the concentrations of C18:0 and C18:1 increased and C16:0 decreased compared to when tallow was fed. Preliminary results from studies on the fertility of the cows indicated minor negative effects on primiparous cows fed the highest amounts of rapeseed products.

Effects of calf management and level of feed supplementation on milk yield and calf growth of Zebu and crossbreed cattle in the semi-arid tropics

The study was conducted on 45 Zebu and 37 crossbred cows that calved in two seasons, the wet and dry season. All cows were fed 2 kg of concentrate mixture daily for 40 days pre-partum in addition to grazing. At calving, cows and their calves were randomly assigned to one of four groups: (1) HAR (n=18) cows were fed a high level of concentrate supplement (4 kg/day) and calves were artificially reared; (2) HRC (n=24) cows were fed a high level of concentrate supplement (4 kg/day) and restricted suckling of calves was practiced; (3) LAR (n=23) cows were fed a low level of concentrate supplement (2 kg/day) and calves were artificially reared and (4) LRC (n=17) cows were fed a low level of concentrate supplement (2 kg/day) and restricted suckling of calves was practiced. Calves in all of the groups were weaned at six months of age. Feeding high or low levels of concentrate supplements to cows was continued for 90 days postpartum. Five animals were excluded from the study for various reasons and the results were derived from 77 cows. Two calves died before weaning. Group LAR had the highest frequency (81.8%) of cows with short lactation lengths (<200 days). Daily milk yield, lactation yield and lactation length were significantly affected by the treatments. Cows in group HAR had a mean lactation yield of 2386±141.77 kg, which was significantly higher than for cows in groups HRS (1539±116.42 kg), LAR (1161±120.84 kg) and LRS (778±131.48 kg). Total milk produced (lactation yield+milk suckled by the calf) by HRS cows averaged 2346.7±101.07 kg, and did not differ (P<0.05) from that of HAR cows, but was significantly higher than for cows in groups LAR and LRS. The interaction, breed×group significantly influenced the daily milk yield and lactation yield. The lactation length of cows in group HRS, of 290.3±11.51 days, was significantly longer than for cows in the other groups, i.e. HAR, LAR and LRS. Cows calving in the wet and dry seasons did not differ in lactation yields, but the lactation length of cows calving in the dry season was significantly longer than for cows calving in the wet season. Crossbred cows had higher daily milk yields and lactation yields than the Zebu cows (P<0.05), while lactation lengths of the two breeds did not differ significantly. Calf liveweight and average daily gain to three months of age were significantly affected by group. Calves in group HRS had a significantly higher liveweight, of 49.5±1.14 kg at three months of age, and a higher average daily gain, of 334.8±11.06 g, than calves in the other groups. Calves born in the wet season had higher liveweights at three and six months of age than calves born in the dry season. Crossbred calves had significantly higher liveweights at three and six months of age, and higher mean daily weight gain to three months of age and up to weaning age than the Zebu calves. The performance of the cows in the HRS group in terms of total milk production, longer lactation length and the added advantage of the higher growth rate of calves than of those in the HAR, LAR and LRS groups shows that restricted suckling coupled with a high level of feed supplementation is important for high performance in Zebu and crossbred cattle.

Effects of different nutritional levels prepartum on the subsequent performance of dairy cows

Abstract Different nutritional levels introduced three weeks before calving and gradually reaching the maximum supply level of 110, 170, 200 or >200 (ad lib) MJ ME/day at calving were studied in two experiments comprising altogether 63 multiparous cows. In Experiment 1, the difference at calving (110 vs. 200 MJ) was gradually eliminated within 4 weeks post partum, while in Experiment 2 treatment differences (ad libitum vs. restricted) were practiced throughout the experiment. The feeds (concentrate, grass hay and grass silage) were fed separately in Experiment 1 and as a total mixed ration in Experiment 2. The experimental period lasted from 4 weeks before calving to 12 or 14 weeks afterwards. The average daily intake of metabolizable energy in cows fed ad libitum was 180 MJ prepartum and 307 MJ in early lactation. A marked decrease in feed intake occurred around calving time, beginning 3–5 days prepartum, among all cows fed a medium or highly nutritional diet at calving. A low nutritional level at calving resulted in a significantly smaller milk yield in the first month postpartum and low serum insulin and high serum free fatty acids concentrations around parturition. Ad libitum feeding did not result in higher milk yield but gave a greater milk protein content and yield and also impaired feed efficiency. Health, fertility, and plasma glucose concentrations did not differ between treatments.

Behaviour of Zebu and crossbed cows in restricted suckling groups.

The aim of this study was to investigate whether Zebu (Bos indicus) and crossbred (Bos indicusxBos taurus) cows differ in maternal related behaviour during restricted group suckling. The behaviours of 20 Zebu and 16 crossbred cows were recorded during two 30min sessions each day after milking when their calves were present for suckling, for a time period of 2 weeks per month for 6 months postpartum. The main activity in both breeds during the 0.5h observation sessions was suckling. However, the two breeds differed significantly in several behavioural aspects. The Zebu cows had longer total duration of suckling than the crossbred cows, per 30min session, 11.8 and 9.4min, respectively. The separate suckling bouts were longer in the Zebu cows (2.8min in Zebu and 2.3min in crossbred) and this breed also had more suckling bouts than the crossbred per session, 3.8 and 3.2, respectively. Zebu cows stayed in close contact with their calves for longer time and directed more agonistic actions against alien calves and cows than the crossbred cows.