Utilization of milk energy by suckling mink kits

A total of 36 mink dams and their litters of 3, 6 or 9 kits were used for determination of milk intake of the suckling young by means of deuterium dilution technique, and chemical composition of milk and of kit bodies. Measurements were performed during lactation weeks 1-4, each week with 3 dams with each litter size. Milk intake was determined over a 48 h measurement period, and by the end of this milk samples were collected and 2 kits (litters of 6 and 9) or 1 kit per litter (litters of 3) were killed for body chemical composition. Based on the results, different models were applied for calculation of the energetic efficiency of milk. Dam milk yield increased steadily from week 1 until week 3 but only slightly from week 3 to 4. The increase declined with increasing litter size, and for dams suckling 9 kits the increment from week 3 to week 4 was only 2 g. The dry matter content of milk increased significantly as lactation progressed, being reflected in crude protein increasing from 6.9% in lactation week 1 to 8.1% in week 4. Milk fat increased concomitantly from 5.6% to 8.0%. In kit bodies, crude protein content increased from 9.4% in week 1 to about 12% in weeks 3 and 4. Body fat content increased from week 1 (4.1%) to week 3 (8.4%) and then declined in week 4 (7.1%). Animals suckled in litters of 3 kits had the highest milk intake and live weight and kits suckled in litters of 9 had the lowest milk intake, live weight and daily gain. In terms of milk intake per g gain kits in litters of 6 were the most efficient, with 4.1 g milk per g body gain. The metabolizable energy requirement for maintenance (MEm) was estimated to 448 kJ/kg(0.75 and the efficiency of utilization of ME for body gain (kg) to 0.67, the estimates being higher (MEm) or in good agreement with previous findings (kg) in suckling mink kits.     

Utilization of milk amino acids for body gain in suckling mink (Mustela vison) kits

The efficiency of utilization of milk amino acids for body gain in suckling mink kits from small (n = 3), medium (n = 6) and large litters (n = 9) was investigated by using 36 mink dams and their litters for measurements during lactation weeks 1 through 4. Measurements on each dam and litter were performed once, hence three dams per litter size each week (n = 9). Individual milk intake of kits was determined, milk samples were collected and kits were killed for determination of amino acid composition. The most abundant amino acids in milk were glutamate, leucine and aspartate making up about 40% of total amino acids. Branched chained amino acids made up slightly more than 20% and sulphur containing amino acids less than 5% of total milk amino acids. In kit bodies the sum of glutamate, aspartate and leucine made up about 32% of amino acids, branched chain amino acids about 16% and sulphur containing amino acids about 4%. The amino acid composition of both milk and bodies changed as lactation progressed with decreasing proportions of essential amino acids. The ratio between body and milk amino acids was constantly over 1 only for lysine, suggesting that it was the most limiting amino acid in mink milk. Milk amino acids were efficiently utilized during week 1, ranging from 74.7% (lysine) to 42.1% (leucine), with an average for essential amino acids of 58.4%. Tendencies for improved utilization of lysine (74.7-78.2%), phenylalanine (61.0-70.0%), histidine (62.4-68.8%), arginine (61.3-70.4%) and all essential amino acids (58.4-60.2%) from week 1 to week 2 were recorded. During weeks 3 and 4, the efficiency declined, and for all essential amino acids the average utilization was 38.1% during week 4.     

Daily milk intake and body water turnover in suckling mink (Mustela vison) kits

Daily (24 h) milk intake and body water turnover were measured in eight litters of suckling mink (Mustela vison) kits (6–9 kits litter⁻¹) during weeks 1–4 post partum using the tritiated water (³HHO) dilution technique. The biological half-life of body water turnover in the mink kits increased linearly from 0.9 days in week 1 (3–5 days post partum) to 1.9 days in week 4 (22–24 days post partum). The daily milk intake varied markedly among the mink kits within a litter and increased significantly with increasing body mass from (mean±SEM) 10.9±0.4 g per kit during week 1 to 27.7±1.0 g per kit during week 4. Throughout the study, male kits were ∼10% heavier and had a significantly higher milk intake than female kits. The results were corrected for water recycling between the dam and her kits, ranging from ∼4 to 15% of the daily milk water intake, and the calculated daily milk yield of the 2 year old lactating mink dams increased from 87±7 g day⁻¹ in week 1 to 190±15 g day⁻¹ in week 4 post partum. The average body growth rate of the mink kits ranged from 2.9 g kit⁻¹ per day in week 1 to 5.4 g kit⁻¹ per day in week 4, and the calculated mean intake of mink milk per unit of body weight gain was remarkably stable at 4.0 (g g⁻¹) during weeks 1–3 post partum, but increased to 5.6 (g g⁻¹) in week 4 post partum. The amount of metabolizable energy supplied to the kits by the daily milk yield of the dam increased from ≈450 to ≈990 kJ day⁻¹, which corresponded well with the calculated daily energy requirements of the kits. The tritiated water dilution technique was found feasible and reliable for repeated measurements of milk intake in suckling mink kits up to 4 weeks of age.     

Utilization of milk fatty acids by the suckling Iberian piglets

A total of 16 pure-bred Iberian (IB) sows, all of them suckling six piglets, were used, eight of them in each of the two consecutive trials (1 and 2). Daily milk yield and composition were determined weekly over a 34-day lactation period. Within each litter, one piglet at birth and four piglets on day 35 of life were slaughtered. Milk intake per piglet tended to be greater in trial 2 (832 v. 893 g/day; P=0.066), but piglets grew at 168±3.3 g/day, irrespective of the trial. In the IB sow milk, the linoleic (LA) : linolenic (LNA) acid ratio averaged 14.6 and 15.2 in trial 1 and trial 2, respectively. A fivefold increase in piglet body fat content was observed over lactation (P<0.001). Most of this fat (81.4%) was present in the carcass. After 34 days of lactation, whole-body relative content of palmitic, palmitoleic, stearic and oleic acids were very close to those in the milk consumed, suggesting direct deposition. Daily deposition of LA derivatives and of LNA and its derivatives was found to be extremely low (<0.02 g, on average). Moreover, some of the arachidonic acid (ARA) in tissues of the IB piglet at birth disappeared throughout the lactating period. An overall fractional deposition for total fatty acids (FA) was 0.409. Fractional oxidation (disappearance) rates were 0.939 and 0.926 for n-6 and n-3 polyunsaturated FA. The overall rate of disappearance for the major non-essential FA (myristic, palmitic, palmitoleic, stearic and oleic acids), estimated as 1−the overall fractional deposition rate, was 0.546. It is concluded that the high degree of FA unsaturation, high oxidation rate of LA and LNA, and poor synthesis of ARA from LA and of docosahexaenoic acid from LNA found in the suckling piglet might increase the energy cost of whole-body fat accretion, a contributor to the observed low efficiency of use of milk energy for growth.     

The effect of diet, parity, year and number of kids on milk yield and milk composition in Maltese goat

The aim of the present study was to study the effects of forage/concentrate ratio, year, parity and number of kids on milk yield (MY), lactation length (LL) and milk composition (fat, protein and lactose) on 180 Maltese goats analysing 530 milk samples collected from 2000 to 2002.

The main average results were: MY = 288.2 kg, LL = 254 d with 3.5% fat, 3.4% protein and 4.6% lactose.

Forage/concentrate ratio significantly affected MY and fat being highest in goats receiving a ratio of 65/35. Milk yield in goats fed with a ratio of 35/65 was richer in fat (3.6%). The protein and lactose content was not affected by the different ratios. The effect of diet on fat content was small but significant. Parity influenced all the factors considered, in particular goats in ≥4th parity, had longer LL (257 d) and consequently a higher milk yield (302.1 kg). Goats kidding twins yielded more milk and had longer lactation (P < 0.001).     

Production and composition of Iberian sow's milk and use of milk nutrients by the suckling Iberian piglet

Sixteen purebred Iberian (IB) sows were used in two consecutive trials to determine the efficiency of conversion of sow's milk into piglet body weight (BW) gain and the relationship between milk protein and body protein retention and between milk energy yield and body energy retention in the nursing IB piglet. In each trial, four sows were selected in order to evaluate their milk production, litter growth and nutrient balance measurements, together with four additional sows for milk sampling. Litter size was equalized to six piglets. Daily milk yield (MY) was determined weekly by the weigh-suckle-weigh technique over a 34-day lactation period. Piglets were weighed individually at birth and then weekly from day 5 of lactation. Milk samples were collected on days 5, 12, 19, 26 and 34 post partum. The comparative slaughter procedure was used to determine piglet nutrient and energy retention. One piglet from each litter was slaughtered at birth and four on the morning of day 35. Total MY was on average 5.175 ± 0.157 kg/day. The average chemical composition (g/kg) of the milk was 179 ± 4 dry matter, 53.4 ± 1.0 CP, 58.5 ± 3.8 fat, 10.4 ± 0.3 ash and 56.9 ± 2.3 lactose. Milk gross energy (GE) was 4.626 ± 0.145 MJ/kg. Milk intake per piglet tended to increase in trial 2 (832 v. 893 g/day; P = 0.066). Piglet BW gain contained (g/kg) 172.1 ± 1.3 protein, 151.5 ± 3.5 fat, 41.4 ± 0.6 ash and 635 ± 3 water and 10.127 ± 0.126 MJ GE/kg. Throughout the 34-day nursing period, the piglets grew at an average rate of 168 ± 3 g/day. The ratio of daily piglet BW gain to daily MY was 0.195 ± 0.002 g/g and the gain per MJ milk GE intake was 41.9 ± 0.5 g/MJ. The overall efficiency of protein accretion (g CP gain/g CP milk intake) was low and declined in trial 2 (0.619 v. 0.571; P = 0.016). Nutrient and energy deposition between birth and weaning were 27.4 ± 0.5 g/day protein, 24.2 ± 0.8 g/day fat and 1615 ± 40 kJ/day energy. Piglet energy requirements for maintenance were 404 kJ metabolizable energy (ME)/kg BW0.75. ME was used for growth with a net efficiency of 0.584. These results suggest that poor efficiency in the use of sow's milk nutrients rather than a shortage in milk nutrient supply might explain the low growth rate of the suckling IB piglet.     

Characterization of oligosaccharides in milk of a mink, Mustela vison

Carbohydrates were extracted from a sample of milk from a mink, Mustela vison (Family Mustelidae). Free neutral and acidic oligosaccharides were isolated from the carbohydrate fraction and their chemical structures were compared with those of white-nosed coati (Nasua narica, Procyonidae) and harbour seal (Phoca vitulina, Phocidae) that we had studied previously. The ratio of free lactose to milk oligosaccharides was similar to that in milk of the white-nosed coati; in both species, this ratio was much lower than that in the milk of most eutherians. The neutral oligosaccharides of mink milk had alpha(1-3)-linked Gal or alpha(1-2)-linked Fuc residues at their non-reducing ends, as in the neutral oligosaccharides of white-nosed coati milk. Some of the neutral and acidic oligosaccharides, determined here, had been found also in harbour seal milk, but the harbour seal oligosaccharides did not contain alpha(1-3)-linked Gal residues.     

Age-related body weight constraints on prenatal and milk provisioning in Iberian red deer (Cervus elaphus hispanicus) affect allocation of maternal resources

Maternal phenotypic characteristics can influence key life history variables of their offspring through maternal effects. In this study, we examined how body size constraints on maternal weight in yearling and subadult compared to adult hinds (age class effects) affected prenatal (calf birth weight, calf to hind weight ratio) and postnatal (milk) provisioning of Iberian red deer calves. Age correlated with all prenatal and postnatal investment traits except calf gains, although correlations were weaker than those with maternal weight. Once the effect of linear increase in weight with age was removed from models, yearlings showed additional reductions in calf birth weight, calf gains, and milk provisioning. The low-calf birth weight might increase the risk of calf mortality during lactation, as this occurs primarily during the first day of life and is strongly related to birth weight. Yearlings showed a greater prenatal allocation of resources in terms of greater calf to hind weight ratio probably as an extra effort by yearling mothers to balance calf neonatal mortality. It might compensate young mothers to produce low-quality calves while still growing rather than waiting for the uncertain possibility of surviving to the next reproductive season.     

In vivo digestomics of milk proteins in human milk and infant formula using a suckling rat pup model

Human milk is the optimal mode of infant feeding for the first several months of life, and infant formulas serve as an alternative when breast-feeding is not possible. Milk proteins have a balanced amino acid composition and some of them provide beneficial bioactivities in their intact forms. They also encrypt a variety of bioactive peptides, possibly contributing to infant health and growth. However, there is limited knowledge of how milk proteins are digested in the gastrointestinal tract and bioactive peptides are released in infants. A peptidomic analysis was conducted to identify peptides released from milk proteins in human milk and infant formula, using a suckling rat pup model. Among the major milk proteins targeted, α-lactalbumin and β-casein in human milk, and β-lactoglobulin and β-casein in infant formula were the main sources of peptides, and these peptides covered large parts of the parental proteins’ sequences. Release of peptides was concentrated to specific regions, such as residues 70–92 of β-casein in human milk, residues 39–55 of β-lactoglobulin in infant formula, and residues 57–96 and 145–161 of β-CN in infant formula, where resistance to gastrointestinal digestion was suggested. In the context of bioactive peptides, release of fragments containing known bioactive peptides was confirmed, such as β-CN-derived opioid and antihypertensive peptides. It is therefore likely that these fragments are of biological significance in neonatal health and development.     

Effects of pigeon pea leaves and concentrate mixture on feed intake,milk yield,and composition of crossbred dairy cows fed native pasture hay

Protein supplements are expensive and not easily accessible under small-scale livestock production systems in Ethiopia and other developing countries, which necessitates investigating the alternative protein sources for cost-effective livestock production. Pigeon pea (Cajanus cajan L. Millsp) leaves (PPLs) are rich in protein and are well-suited for feeding small ruminants; however, the effect of inclusion of PPL in the concentrate mixture (CM) on the performance of dairy cows was not well documented. This experiment was conducted to evaluate the effect of supplementation of PPL and CM to native pasture hay-based rations on feed intake, milk yield and composition, and blood metabolites of crossbred dairy cows (Holstein × Zebu). A 4 × 4 Latin square design with three replications, balanced for carryover effects, was used for this study. The treatments included native pasture hay provided ad libitum as a basal diet, supplemented with a CM alone (T1), the inclusion of 10% of PPL in the CM (T2), 20% PPL in the CM (T3), or 30% PPL in the CM (T4). Supplements were isocaloric and isonitrogenous. Total DM intake (hay + supplement intake) was similar (P > 0.05) among treatments. Hay intake was greater (P = 0.05) for T1 and T2 than for T4, while supplement intake was the least for T1 (P < 0.05). The treatment groups T2, T3, and T4, where PPL was included, had similar (P > 0.05) supplement intake. Feed intake, milk yield and composition, feed conversion efficiency, body condition score, serum total protein, albumin, globulin, glucose, triglyceride, urea N, creatinine, and cholesterol were similar (P > 0.05) among treatments. The inclusion of up to 30% of PPL in the CM resulted in a comparable performance of crossbred dairy cows as supplementation with CM under the conditions of the current experiment. Therefore, further study is required to evaluate the effect of the inclusion of a higher level of PPL in the concentrate mixture on the performance of lactating crossbred dairy cows.     

Impact of three THI levels on somatic cell count,milk yield and composition of multiparous Holstein cows in a subtropical region

In Egypt, cow's milk represents 52.11% of the total milk production. Climatic condition is mainly expected to impact the welfare and productive performance of livestock animals. Thus, we aimed to explore the impact of temperature-humidity index (THI) on somatic cell count (SCC), milk production and composition on daily milk test records (33600) of Holstein cows under subtropical Egyptian conditions with different levels of THI. Our results revealed that daily milk yield and composition (fat%, protein %, yielded fat, yielded protein and the percentage of lactose) were higher in low THI (31.91 kg, 3.91%, 3.22%, 418 kg, 349 kg and 4.20%, respectively) when compared with high THI. SCC significantly increased 36% from low to high THI. In addition to, it was increased with advanced parities 231.11% from 2nd to 7th parities. At high THI level, SCC was negatively correlated with total MY (r=−0.12 P<0.05), 305 MY (r=−0.16 P<0.05), protein % (r=−0.15 P<0.01), fat% (r=−0.14 P<0.01) and lactose % (r=−0.26 P<0.01). The current study concluded that dairy cows performance was better in most of the investigated parameters at low THI than those in high THI. Thus, indicating a detrimental effect of THI on both welfare and economic return.     

Interaction of calf suckling, use of oxytocin and milk yield with reproductive performance of dairy buffaloes

Calf suckling and oxytocin injections are commonly used for pre-milking stimulus in dairy buffaloes under field conditions. A study was conducted to investigate effect of these treatments on reproductive performance. Fifty one Nili-Ravi buffaloes were monitored from parturition up to 150 days postpartum through rectal examination. Data on milk yield, body condition score (BCS) and reproductive parameters were recorded weekly. Postpartum ovulation interval (POI) was determined by presence of an ovulation depression or a very soft corpus luteum haemorrhagicum and was confirmed through milk progesterone levels (MPL). Suckling was used to stimulate milk let down, and where the calf had died, injection of oxytocin was resorted to. Milk samples were analyzed for MPL using radioimmunoassay (RIA) and fat; and milk yield was converted to 4% fat corrected milk (FCM). The mean postpartum uterine involution length (PUI) was 34.30 ± 1.33 days. Mean POI was 59.37 ± 4.76 days and mean postpartum estrus interval (PEI) was 69.03 ± 6.03 days. Suckling period averaged 26.40 ± 5.57 days and correlated with POI (r = 0.19, P < 0.01) and PEI (r = 0.23, P < 0.01). POI was shortest in buffaloes suckled for one month (P < 0.05). Oxytocin was used with a mean dosage of 7.50 IU, delaying placental expulsion time (PET) and POI but shortening PEI. BCS shortened PET, POI and PEI (P < 0.01). Mean FCM was 14.50 ± 0.20, ranging from 2 to 35 kg/d; and was higher in estrus group; correlating positively with POI (r = 0.31, P < 0.01). MPL were 1.37 ± 0.17 ng/ml and increased after ovulation, remaining greater than 1.5 ng/ml from Day 4 to 14 of the estrus cycle, followed by a rapid decline up to next estrus. BCS in buffaloes resuming oestrus was constantly higher than those failing to resume ovarian cyclicity. Live weight, prepartum was 510.0 ± 5.9 kg with a loss of 3.7 ± 2.12 kg, 30 days postpartum. The present study suggests a lower reproductive efficiency of dairy buffaloes under the peri-urban farming system reflected by ovarian cyclicity in 68.63% buffaloes within 150 days postpartum and silent estrus in 51.5% of the cases. Increasing suckling duration and use of oxytocin delayed POI, however, POI was shortest in buffaloes suckled for one month. The high yielding buffaloes also manifested better reproductive cyclicity; while moderate yielder showed shorter ovulation intervals and higher conception rate.     

Influence of maternal dietary calcium levels on milk zinc, calcium and phosphorus contents and milk production in rats

The aim of this study was to analyze zinc (Zn), calcium (Ca) and phosphorus (P) contents in milk and the lactational performance in rats fed different Ca levels. Female Wistar rats were fed during pregnancy and lactation with experimental diets containing 20% protein and high (0.90%, HCa), normal (0.60%, NCa) or low (0.20%, LCa) Ca levels. Milk samples were collected after 15 days to determine the milk mineral composition. Pup weight was recorded from birth to weaning (litter size: 6-8 pups) to determine weight gain and calculate milk production. At delivery there were no significant differences in the body weight of the pups between the groups, but at day 15, the LCa group showed lower values than both NCa and HCa groups (p<0.05). The weight gain of the LCa group was significantly lower than of the HCa and NCa groups, between delivery and day 5 (p<0.05). This reduced rate of weight gain led to the LCa group reaching weaning weight later than the other groups. Milk production (g/pup/day) was significantly lower when dams were fed the LCa than the NCa and HCa diets (p<0.05). There were no significant differences among the groups in milk Ca, P and Zn levels and Ca/P ratio. The body mineral composition of the pups at birth did not differ between the groups; at weaning, however, both LCa and HCa groups had lower element contents than the NCa group (p<0.05). In conclusion, dams fed with a diet containing low Ca levels produced smaller volumes of milk and their pups reached weaning weights later than the other groups. As the milk mineral composition was not affected, it can be hypothesized that in dams fed low dietary Ca, the smaller milk yield might have been a way of maintaining milk quality. High Ca levels affected neither pregnancy outcome nor lactational performance.     

The effect of heat incubators on chilled mink kits

Hypothermia is considered a major risk factor increasing kit mortality in farmed mink. We studied the effects of reheating chilled mink kits. From each of 27 litters, three 1-day-old kits were exposed to one of three treatments: (i) chilling and reheating in a farm incubator (INCU), (ii) chilling and reheating in home nest (HOME), and (iii) control, remained in nest (NEST). During cold exposure (8 °C) mink kits were active in average 67% of the time before they turned inactive; the latency until inactivity averaged 12.3 (0.8) min. We suggest that kit behaviour during early cooling may function to increase chances of eliciting maternal care, and we found that duration of kit activity increased with body weight in 1-day-old kits (P < 0.001). In addition, the most active kits had a shorter latency of coming inactive (P = 0.002), suggesting that the behaviour is energy costly. The kit mortality was low (5 out of 81), making statistical analysis of mortality infeasible. We found no treatment effects on weight gain over 7 days. We did not find any additional effect of the traditional incubator used in reheating chilled 1-day-old mink kits, as the dam in the home nest appeared as efficient to reheat a small chilled kit.     

Changes in milk composition during lactation in three species of insectivorous bats

Changes in milk composition are described for three species of free-ranging insectivorous bats (Myotis lucifugus, M. velifer, and Tadarida brasiliensis) from early to mid (peak) lactation. Dry matter and energy concentrations in milk increased from early to mid-lactation. In M. lucifugus and T. brasiliensis, but not M. velifer, these increases were due largely to a rise in fat concentration, since protein and carbohydrate remained relatively constant. Energy content of milk (kJ·g^-1) for each species from early through mid-lactation was related to dry matter (DM) as follows: M. lucifugus (y=0.31 DM-0.32, r ²=0.68), M. velifer (y=0.48 DM-5.08, r ²=0.99), and T. brasiliensis (y=0.37 DM-1.51, r ²=0.61). Comparison of the effect of sampling method on milk composition of T. brasiliensis indicated that fat, dry matter, and energy concentrations increased significantly from pre-dawn to prenoon samples. Relatively high fat and low water levels in T. brasiliensis milk may reflect the limited access that lactating females have to free water, as well as need to minimize mass of stored milk during long foraging trips. Conversely, lower fat concentrations and higher water levels in milk in M. lucifugus and M. velifer may relate to the propensity for colonies of these two species to roost and forage near bodies of water. In addition, differences in milk fat concentrations observed among the three species may correlate to daily suckling schedules. Females of T. brasiliensis, for example, roost apart from and suckle their young on a regular daily schedule, whereas both species of Myotis roost with their pups and appear to suckle them on demand.Abbreviations bm body mass - DM dry matter - T _a air temperature     

应用益生菌监测牛奶抗生素残留

目的 探索肠道益生菌在抗生素残留监测中的应用并建立牛奶中多种抗生素残留的微生物学筛检方法。方法 厌氧培养分离健康人肠道益生菌并用纸片扩散法检测其对四环素、红霉素、青霉素、庆大霉素、氯霉素和万古霉素的敏感性。根据药敏结果及产酸能力选择工作菌株。建立基于厌氧培养的益生菌抗生素残留筛检方法并优化实验条件,测定其对不同抗生素的检测限,通过测定加标模拟阳性和阴性样本计算方法的准确性。结果 短双歧杆菌A2可用于牛奶抗生素残留筛检。应用短双歧杆菌筛检牛奶中四环素、红霉素和青霉素的检测限分别为80 μg/L、40 μg/L和3 μg/L,检测加标四环素、红霉素和青霉素的牛奶样品准确性为100.0%、92.5%和90.0%,无假阴性结果。结论 应用益生菌的筛检方法敏感、简便,对环境和操作者友好,适用于监测牛奶中四环素、红霉素和青霉素等多种抗生素。     

Effects of flaxseed supplementation on milk production,milk fatty acid composition and nutrient utilization by lactating dairy cows

Twelve multiparous Holstein cows at 72 ± 20 days in milk were used in a switch-back design with 14-d periods to determine the effect of replacing barley grain into a dairy total mixed ration with micronized or raw flaxseed on nutrient digestibility, milk yield, milk composition. Total mixed diets were (DM basis) 50% barley silage, 50% concentrate mix mainly rolled barley grain and canola meal. Diets were supplemented with 1 kg raw (RF) or micronized (MF) flaxseed to substitute 1 kg of rolled barley grain (C). Neutral detergent fibre, ADF and CP digestibility of the diets were not significantly affected by supplementation; however, calcium digestibility was reduced by 62% and 46% when raw and micronized flax were fed, respectively. Milk yield (38.3, 39.6, and 38.4 kg/d for diets C, RF and MF, respectively) was similar for all diets. Milk fat (3.50, 3.48, and 3.52%) and protein (3.31, 3.34, and 3.31%) for diets C, RF and MF, respectively, were not affected by treatment diets. Concentrations of c9, t11 conjugated linoleic acid (CLA; 0.51, 0.72 and 0.76 g/100 g fatty acids) in milk fat increased (P < 0.05) similarly among the two flaxseed supplemented diets. The RF and MF diets significantly increased the C18:1, C18:1 trans-11, C18:2 cis-9, cis-12 and C18:3 in milk fat however, C12:0, C14:0 and C16:0 were significantly reduced compared with control. Replacing barley grain with flaxseed in the diet of lactating cows increased the beneficial fatty acids in milk without depressing nutrient digestibility. Micronization of flaxseed did not reveal any advantage over raw flaxseed.     

双歧杆菌对母乳低聚糖利用的研究进展

母乳低聚糖(human milk oligosaccharides,HMOs)是一类存在于人乳中复杂的混合低聚糖,是母乳中的重要成分,在婴幼儿生长发育中起到重要作用。母乳低聚糖可作为影响肠道微生物群组成的益生元,可选择性地促进母乳喂养婴儿肠道双歧杆菌的生长。婴儿肠道内相关的双歧杆菌具有糖苷酶和转运蛋白等分子工具,使其能够代谢HMOs,且代谢过程具有菌株特异性。本文对2′ 岩藻糖基乳糖、3′ 岩藻糖基乳糖、3′ 唾液酸乳糖、6′ 唾液酸乳糖、乳糖 N 四糖、乳糖 N 新四糖等常见HMOs的结构和特点进行总结,并讨论不同双歧杆菌对不同HMOs的利用特点和机制,为开发针对不同双歧杆菌的特异性益生元提供相应的理论指导。     

Effects of evaporative cooling on the regulation of body water and milk production in crossbred Holstein cattle in a tropical environment

The aim of this study was to determine how evaporative cooling modifies body function with respect to water metabolism and other variables relevant to milk synthesis in crossbred cattle. The study was conducted on two groups of 0.875HF:0.125RS crossbred Holstein cattle (87.5%) housed in an open-sided barn with a tiled roof (non-cooled animals) and in a close-sided barn under an evaporative cooling system (cooled animals). The maximum ambient temperature and relative humidity for the non-cooled group were 33 degrees C and 61%, with the corresponding values for the evaporatively cooled barn being 28 degrees C and 84%, respectively. The temperature humidity index (THI) of under non-cooled conditions was higher (P < 0.05) than that in the cooled barn. Rectal temperatures and respiration rates of non-cooled animals were higher (P < 0.05) than those of cooled animals. Daily dry matter intake (DMI) of cooled animals was higher while water intakes were lower (P < 0.05) than those of non-cooled animals. The mean absolute values of plasma volume, blood volume, and extracellular fluid (ECF) of cooled animals were significantly higher (P < 0.05) than those of non-cooled animals throughout all stages of lactation. Milk yields of cooled animals were higher by 42%, 36% and 79% on average than those of non-cooled animals during early-, mid- and late-lactation, respectively. The decline in milk yields as lactation advances was markedly apparent in late-lactating non-cooled animals, while no significant changes in milk composition at different stages of lactation were observed in either group. Mean arterial plasma concentrations, arteriovenous concentration differences (A-V differences) and the extraction ratio across the mammary gland for acetate, glucose and triglyceride of cooled animals were not significantly different compared with values for non-cooled animals. No differences were seen in plasma hormonal levels for triiodotyronine (T(3)) and insulin-like growth factor-1 (IGF-1), but plasma cortisol and thyroxine (T(4)) levels tended to be lower in non-cooled animals. This study suggests that low cooling temperature accompanied by high humidity influences a galactopoietic effect, in part through increases in ECF, blood volume and plasma volume in association with an increase in DMI, which partitions the distribution of nutrients to the mammary gland for milk synthesis. Cooled animals were unable to maintain high milk yield as lactation advances even though a high level of body fluids was maintained during long-term cooled exposure. The decline in milk yield, coinciding with a decrease in net energy for lactation as lactation advances, could be attributed to a local change within the mammary gland.     

Early prepartum shearing increases milk production of wool sheep and the weight of the lambs at birth and weaning

The use of mid prepartum shearing has been described as a possible tool to increase the weight of the lambs at birth and at weaning. The effect of prepartum shearing (53 days of gestation) on production and chemical composition of milk, weight of the lambs at birth and weaning and growth rate were evaluated in this trial. Twenty Polwarth ewes were inseminated with rams of the same breed in May (autumn), 2009. All ewes bore singletons and were maintained together under cultivated grazing conditions, during the experimental period. The ewes were allocated to two treatments groups, based on expected day of parturition, body weight and BCS of the dams. Ten ewes were shorn at 53 days of gestation (S53) and 10 ewes were kept unshorn during gestation (US). Milking of the ewes was recorded 7 days after parturition, and this was repeated weekly for 15 weeks. Milk production of the S53 ewes was 22.2% higher (P < 0.05), when compared to US control ewes - with no change in the milk composition. At lambing, the lambs born to the S53 ewes were 1.41 kg (P < 0.05), and at weaning 4.5 kg heavier (P < 0.05), than lambs born to US ewes. In conclusion, it can be said that the higher weaning weight of the S53 lambs was the result of both a higher birth weight and an increased growth rate up to weaning in part, due to an improved milk production of the ewes.