Post-ruminal or intravenous infusions of carbohydrates or amino acids to dairy cows 1. Early lactation

The objectives of this study were to compare the effects of post-ruminal and intravenous infusions of wheat starch or glucose (CHO) or a mixture of amino acids (AA) on milk protein yield, nitrogen utilisation, plasma metabolites and mammary extraction rate of dairy cows in early lactation. Eight cow, ruminally fistulated, was assigned to two 4 × 4 Latin squares during 14-day periods, where the last 7 days were for infusions. Infusions were: (1) starch in the abomasum (SP), (2) glucose in the blood (GB), (3) AA in the abomasum (AP), and (4) AA in the blood (AB). The experiment started 54 ± 4 days (mean ± s.e.) post partum (milk yield 33.4 ± 1.7 kg). Daily amounts of nutrients infused were 378, 365, 341, and 333 g for SP, GB, AP and AB, respectively. The cows were fed a basal diet consisting of a concentrate mixture and grass silage (55:45 on dry-matter (DM) basis), and DM intake was 17.2 kg/day. Milk production was affected by site of infusion within substrate, whereas infusion substrates within infusion site (CHO or AA) were of minor importance. Compared with SP infusion, GB infusion increased ( P < 0.05) milk protein yield and concentration by 55 g and 1 g/kg. The AB infusion tended to ( P < 0.10) increase milk yield and ECM and increased ( P < 0.05) protein yield and concentration by 1.8 and 2.2 kg, 83 g and 1.1 g/kg compared with AP infusion, respectively. Nitrogen balance data indicated higher losses of metabolic faecal nitrogen (MFN) by abomasal than by intravenous infusions, and an increased ( P < 0.05) catabolism for AP and AB infusions compared with SP and GB infusions. GB infusion did not increase ( P>0.10) plasma glucose or insulin concentrations above that of SP infusion. Compared with the SP infusion, the GB infusion had minor effect on plasma AA. AP infusion increased ( P < 0.05) plasma non-essential AA (NEAA) concentration compared with AB infusion, whereas infusion site of AA had no effect ( P>0.05) on essential AA (EAA) or branched-chain AA (BCAA). Although a higher milk protein synthesis was observed for AB infusion, the mammary extraction rate was not higher ( P>0.05) than for AP infusion. Across infusion site, AP and AB infusions increased plasma concentration of EAA and BCAA, but compared with GB infusion, the mammary extraction rates tended ( P < 0.10) to be lower. It is concluded that abomasal nutrient infusion increases loss of MFN and that the gastrointestinal metabolism influences the nutrients available for milk synthesis. Our conclusion is that when glucose was infused, AA limited a further milk protein synthesis, but when AA was infused, glucose or energy substrate might have been the limiting factor. Our results verify that glucogenic substrates are limiting when cows are in negative energy balance.     

Impact of fat source and dietary fibers on feed intake,plasma metabolites,litter gain and the yield and composition of milk in sows

Sow lactation diets often include fat sources without considering the impact on digestion, metabolism and performance. Fiber ingredients may reduce feed intake and are often completely excluded from lactation diets, although locally available ingredients may be cost-efficient alternatives to partly replace cereals in lactation diets. Thus, a standard lactation diet low in dietary fiber, and two high-fiber diets based on sugar beet pulp (SBP) or alfalfa meal (ALF) were formulated. The SBP diet was high in soluble non-starch polysaccharides (NSP), whereas ALF being high in insoluble NSP. Each diet was divided in three portions and combined with 3% soybean oil (SOYO), palm fatty acid distillate (PFAD), or glycerol trioctanoate (C8TG) as the dietary fat source. Equal amounts of metabolizable energy were fed to 36 second parity sows from day 105 of gestation and throughout lactation to study the impact on feed intake, plasma metabolites, milk production and litter performance. Backfat thickness and BW of sows were recorded on days 3, 17 and 28 of lactation; blood was sampled on days 3 and 17; milk samples were obtained on days 3, 10, 17 and 24 of lactation; and piglets were weighed on days 2, 7, 14, 21 and 28 of lactation. Litter gain and milk yield during late lactation were greater in sows fed C8TG or SOYO than in sows fed PFAD (P=0.05), whereas loss of BW (P=0.60) and backfat (P=0.70) was unaffected by fat source. Milk protein on days 3 and 10 of lactation were lower in C8TG and SOYO sows, than in PFAD sows (P<0.05). The lowest concentration of plasma lactate on day 3 (P<0.05) and plasma acetate on day 17 (P<0.05) was observed in C8TG sows. Milk yield was unaffected by fiber treatment (P=0.43), whereas milk protein concentration was lowest in ALF sows (P<0.05). Feed intake tended to be lower (P=0.09), and litter gain during the 3^rd week of lactation was decreased (P<0.05) in SBP sows. In conclusion, performance was enhanced in SOYO and C8TG compared with PFAD sows, possibly associated with reduced energy intake in PFAD-fed sows. Furthermore, the SBP diet seemed to impair feed intake and litter gain at peak lactation, suggesting that effects of the dietary fiber fraction on energy intake determines the potential inclusion level of fiber-rich ingredients.     

Variation in blood leucocytes,somatic cell count,yield and composition of milk of crossbred goats

Ten multiparous crossbred goats, five each of alpine × beetal (AB) and saanen × beetal (SB) were selected from the National Dairy Research Institute goat herd immediately after parturition. These were managed as per the practices followed in the institute’s goatherd. Blood and milk samples were collected at biweekly intervals from day 14 post-kidding for 22 weeks (154 days). Somatic cell count, electrical conductivity, fat, protein and lactose contents of milk were determined using standard methods. In the blood samples total leucocytes and differential leucocytes were also determined. Somatic cell counts were high immediately after parturition on day 14 of lactation and declined gradually with advanced lactation. There were individual variations (P < 0.01) in somatic cell counts between different lactation periods. Somatic cell count of milk was negatively correlated with neutrophils only (P < 0.05) and was neither correlated with milk yield, or with fat, protein, lactose content of milk. Electrical conductivity of milk was low up to four weeks of lactation and thereafter increased as the lactation advanced. Lactose content of milk declined gradually with the advancement of lactation. Fat content of milk was stable up to the eighth week and thereafter increased with advancement of lactation while the protein content of milk did not change significantly during lactation.     

Effects of prolonged intravenous infusions of adrenaline on glucose utilization, plasma metabolites, hormones and milk production in lactating sheep

Lactating ewes received continuous intravenous infusions of adrenaline (0.05 micrograms/kg liveweight) for 4 days. Prior to, during and after adrenaline infusions, milk yield and composition were monitored. Plasma concentrations of metabolites and hormones were measured each day and glucose biokinetics were measured in non-steady state at the start and end of adrenaline infusions. During adrenaline infusion, milk yield and content of solids-not-fat decreased and milk fat content was reduced on the first day of infusion. Plasma glucose was raised throughout the period of adrenaline infusion, plasma lactate increased over the first 4 h from the start of infusion and plasma non-esterified fatty acids increased for 2 h at the start of infusion and tended to increase during the first 2-3 h after withdrawal of adrenaline. Plasma growth hormone remained relatively stable except for a marked increase at 30 min after withdrawal of adrenaline. At the start and immediately after withdrawal of adrenaline infusion plasma insulin was increased approximately twofold. Glucose production, but not utilization, increased at the start of infusions. Immediately after withdrawal of adrenaline glucose utilization increased 2.5-fold with a smaller response in glucose production. There was essentially no change in glucose clearance during adrenaline infusion but a marked increase occurred after withdrawal of adrenaline.     

The CSN1S1?N and F alleles identified by PCR-SSCP and their associations with milk yield and composition in Chinese dairy goats

A method was depicted to identify null allele CSN1S1 N and low allele CSN1S1 F of the CSN1S1 gene of goat using PCR-SSCP (polymerase chain reaction-single strand conformation polymorphism). First, primer A was designed to amplify the exon 9 of CSN1S1 gene which produced three genotypes AA, AB, and BB. Among these three genotypes, only AA and AB individuals had a cytosine deletion at exon 9 after DNA sequencing, which cannot be used to identify the N and F alleles. Therefore, primer B was used to amplify intron 14 of CSN1S1 of described AA and AB individuals. Genotypes FF, FN and NN were detected within AA individuals and genotypes FO and NO were detected in the above AB individuals. The frequencies of F and N alleles in 708 samples from Xinong Saanen (XS) and Guanzhong (GZ) dairy goat breeds were 0.1139, 0.0927, and 0.2376, 0.1193, respectively. In 268 XS samples, the individuals with NN genotype contained a significant lower protein content than that of other genotypes (P<0.01). Individuals of FF genotype had significant higher milk yield than that of NO genotype in the first milk lactation of 202 XS individuals (P<0.05). Therefore, the variability at CSN1S1 locus contains enough genetic diversity to be potentially useful in improving the quality and production of milk in Chinese dairy goat breeds.     

Associations between genetic merit for milk production and animal parameters and the fertility performance of dairy cows

Relationships between genetic merit for milk production and animal parameters and various parameters of reproductive performance were examined using multilevel binary response analysis in a study of 19 dairy herds for three successive years, representing approximately 2500 cows per year. The proportion of cows intended for rebreeding that were back in-calf again within 100 days of calving (ICR-100) and the proportion of cows that reappeared again with 365 (RR-365) and 400 days (RR-400) of a previous calving were considered in addition to the traditional measures of reproductive performance. Each 100-kg increase in genetic merit for milk yield was associated with an increased interval to first service (IFS) and calving index (CI) of 1.4 ( P < 0.001) and 1.8 days ( P < 0.001), respectively, a 0.5% increase ( P < 0.05) in calving rate to first insemination (CR-1) and 0.8% increase in RR-400. Each £10 increase in £PIN (the economically weighted yield selection index used in the UK that takes account of butterfat and protein yields) was associated with an increased IFS and CI of 1.5 ( P < 0.001) and 3.0 days ( P < 0.001), respectively. Cows with increased genetic merit for milk yield and £PIN were more likely to re-calve (RR-overall; P < 0.001). Each 1000-kg increase in 305-day milk yield was associated with an increased IFS and CI of 3.2 ( P < 0.001) and 7.8 days ( P < 0.001), respectively, and a 13.6 ( P < 0.001), 22.4 ( P < 0.001), 19.9 ( P < 0.001) and 19.0% ( P < 0.001) decrease in CR-1, ICR-100, RR-365 and RR-400, respectively. A 10-kg increase in maximum yield was associated with a 6.6-day increase in CI ( P < 0.001) and a 14.9 ( P < 0.001), 18.3 ( P < 0.001), 9.6 ( P < 0.05) and 14.2% ( P < 0.001) decrease in CR-1, ICR-100, RR-365 and RR-400, respectively. Fertility performance was also associated with season of calving, lactation number and dystocia score. Level of production had a larger effect on fertility performance than genetic merit for milk production suggesting that infertility at an individual cow level is more likely to be associated with increased production and an inability to meet the nutritional requirements of the cow.     

Ovine insulin induced-gene-2: molecular characterization,polymorphisms and association with milk traits

The aim was to characterize the INSIG-2 gene in Sarda sheep and to highlight associations between polymorphisms and milk traits. Two-hundred ewes, in their third or fourth lactation who lambed a single lamb between 20th and 30th of November, were chosen. Monthly individual milk yield was recorded and from each ewe a sample of milk was taken to analyze fat and protein content. PCR–RFLP and DNA sequencing were carried out to detect polymorphisms. Five exons have been characterized and five mutations have been found G88A, 436TCAGdel, A471G, C1071T and T1737G all in the intronic regions. The ovine sequence and related variations were deposited in GenBank with accession number JX843812.1. The animals carrying AA genotype at position 88 showed a lower milk fat concentration than those with the AG or GG genotype (P < 0.05). A lower milk fat concentration was registered also in the animals with the TCAG deletion in position 436 (P < 0.05) and in the animals carrying AA genotype at position 471 compared to those with the AG or GG genotype (P < 0.05). Moreover, the animals carrying CC genotype at position 1071 had a greater milk yield than those with CT or TT genotype (P < 0.05) while ewes with TT genotype showed a higher milk protein concentration compared to the others (P < 0.05). A total of 11 haplotypes were detected but no significant associations with milk traits were found. In conclusion for the first time the complete coding sequence of INSIG-2 gene and its association with milk trait has been reported in this study.     

Meta-analysis of Genetic Structure and Association of Prolactin Gene with Performance Traits in Dairy Cattle in India

The present meta-analysis was carried to provide the more reliable estimates of gene frequency and association of Rsa 1 generated candidate genotype of prolactin gene within exon-3 with performance traits in 1198 Indian dairy cows using data from 15 published studies. Six genetic models viz., codominant (AA vs. AB, AA vs. BB and AB vs. BB), dominant (AA+AB vs. BB), completely over dominant (AA+BB vs. AB) and recessive (AA vs. AB+BB) were used to obtain standardized mean difference (SMD) between genotypes. Meta-analysis showed that the gene frequency of A allele (156 bp) was 0.60 (95% confidence interval (CI) 0.54, 0.65). In association analysis, cows with AB genotype [SMD?=?0.65, 95% CI 0.00, 1.30] had significantly (P?<?0.05) higher lactation milk yield (LMY) as compared to BB genotype, whereas AA and AB genotypes had similar trend. Likewise, AA?+?AB also had larger effect [SMD?=?2.31, 95% CI 0.21, 4.10] on LMY as compared to BB. Cows with AB genotype had significantly lower age at first calving (AFC) with small effect [SMD (AA vs. AB)?=?1.38, 95% CI 0.06, 2.70] and medium effect [SMD (AB vs. BB)?=????3.83, 95% CI???6.41,???1.24] as compared to cows with AA and BB genotypes, respectively. This finding was confirmed under dominant and completely over dominant models. In case of fat%, AA genotype showed negative effect (SMD?=????0.51, 95% CI???0.84,???0.17) under recessive model. It was concluded that the propagation of allele A is promising to help dairy farmers to improve the genetic quality of their dairy cows.

     

Effects of yeast culture supplementation from late gestation to weaning on performance of lactating sows and growth of nursing piglets

Dietary yeast culture supplementation can contribute to the performance and health of sows and piglets, but few studies have focused on the relationships between the effects of yeast culture and gut microbiota. This study investigated the effect of yeast culture (Saccharomyces cerevisiae) supplementation from late gestation to weaning on the reproductive performance of lactating sows and their faecal microbiota. One hundred and six purebred Landrace sows, of parities two to six were selected and randomly assigned to a control (CON) and yeast culture supplementation (YC) groups based on parity and back fat thickness. The YC sows were individually fed with yeast culture at a dose of 24 g/d from day 90 of gestation to parturition and 40 g/d during lactational period. Blood samples were collected from sows on d 110 of gestation and at weaning at day 21 of lactation for plasma hormone and immunoglobulin analysis. Colostrum and milk on day 20 of lactation were collected for composition analysis. Faecal samples from sows on day 110 of gestation and day 20 of lactation were collected for short-chain fatty acid and faecal microbial analysis. Results showed that the farrowing performance of YC sows did not differ significantly from the CON group (P > 0.05). The average daily feed intake by the YC group during the lactation period was significantly increased by 9.98% (P = 0.004), the weaning-to-oestrus interval was shortened by 0.96 d (P = 0.046) and average daily weight gain of piglets increased by 7.14% (P = 0.036) compared with the CON group. Yeast culture supplementation also significantly improved the average daily milk yield in the first week of lactation (P = 0.035), lactose content in colostrum (P = 0.046), protein (P = 0.033) and DM (P < 0.001) content of milk. In the YC group, concentrations of plasma ghrelin (P = 0.02) and IgG (P = 0.015) were increased compared with the CON group, while that of glucagon-like peptide-1 was decreased (P = 0.006) on d 110 of gestation. The 16S rRNA gene sequencing showed that faecal microbiota changed at taxonomic levels with yeast culture addition (P < 0.05). Dietary yeast culture supplementation from late gestation to lactation improved feed intake, immunity status, milk yield, milk quality and faecal microbiota of sows, resulting in the improved growth performance of piglets.     

Added dietary cobalt or vitamin B12, or injecting vitamin B12 does not improve performance or indicators of ketosis in pre- and post-partum Holstein-Friesian dairy cows

Vitamin B₁₂ is synthesised in the rumen from cobalt (Co) and has a major role in metabolism in the peri-paturient period, although few studies have evaluated the effect of the dietary inclusion of Co, vitamin B₁₂ or injecting vitamin B₁₂ on the metabolism, health and performance of high yielding dairy cows. A total of 56 Holstein-Friesian dairy cows received one of four treatments from 8 weeks before calving to 8 weeks post-calving: C, no added Co; DC, additional 0.2 mg Co/kg dry matter (DM); DB, additional 0.68 mg vitamin B₁₂/kg DM; IB, intra-muscular injection of vitamin B₁₂ to supply 0.71 mg/cow per day prepartum and 1.42 mg/cow per day post-partum. The basal and lactation rations both contained 0.21 mg Co/kg DM. Cows were weighed and condition scored at drying off, 4 weeks before calving, within 24 h of calving and at 2, 4 and 8 weeks post-calving, with blood samples collected at drying off, 2 weeks pre-calving, calving and 2, 4 and 8 weeks post-calving. Liver biopsy samples were collected from all animals at drying off and 4 weeks post-calving. Live weight changed with time, but there was no effect of treatment (P>0.05), whereas cows receiving IB had the lowest mean body condition score and DB the highest (P<0.05). There was no effect of treatment on post-partum DM intake, milk yield or milk fat concentration (P>0.05) with mean values of 21.6 kg/day, 39.6 kg/day and 40.4 g/kg, respectively. Cows receiving IB had a higher plasma vitamin B₁₂ concentration than those receiving any of the other treatments (P<0.001), but there was no effect (P>0.05) of treatment on homocysteine or succinate concentrations, although mean plasma methylmalonic acid concentrations were lower (P=0.019) for cows receiving IB than for Control cows. Plasma β-hydroxybutyrate concentrations increased sharply at calving followed by a decline, but there was no effect of treatment. Similarly, there was no effect (P>0.05) of treatment on plasma non-esterified fatty acids or glucose. Whole tract digestibility of DM and fibre measured at week 7 of lactation were similar between treatments, and there was little effect of treatment on the milk fatty acid profile except for C15:0, which was lower in cows receiving DC than IB (P<0.05). It is concluded that a basal dietary concentration of 0.21 mg Co/kg DM is sufficient to meet the requirements of high yielding dairy cows during the transition period, and there is little benefit from additional Co or vitamin B₁₂.     

Responses of milk protein,arterial AA concentration,and mammary AA metabolism to graded abomasal casein infusion in lactating goats

It has been generally assumed in postruminal protein or AA infusion studies that casein or AA mixtures mimicking the essential AA (EAA) composition of milk approach ‘ideal protein’ status, but the differences in postabsorptive metabolism of individual EAA may bring the assumption into question. Graded amounts of caseinate sodium were abomasally infused into lactating goats, and concentrations in the plasma of carotid, mammary uptakes and utilization efficiencies of amino acids were monitored in the present study. The results indicated that arterial concentrations of all the amino acids, except for Arg were increased with the increase of caseinate sodium infused (P < 0.05). The increments in plasma concentration differed with individual EAA. Concentrations of Ile, Leu, and Lys increased about two-folds, and that of Met, Thr, Phe, and His increased 58.33, 32.5, 29.87, and 61.66%, respectively, when data of the 99 g/day and the control treatment was compared. Mammary extraction efficiencies of Arg, Thr, Lys, Leu, and Phe increased with graded casein infusion (P < 0.05), while those of the other EAA were not significantly changed (P > 0.05). Mammary extraction efficiencies of individual non-essential amino acids (NEAA) varied greatly, and ranged from 9.18 to 33.89% in the control treatment. Except for Pro, mammary extraction efficiency of NEAA increased with graded casein infusion. Mammary uptake to milk output ratios (U/O) of sequestered AA was generally increased with the increase of casein infused, but that of Thr, His, and Ala was not insignificantly changed (P > 0.05). Compared with the data of previous researchers, the U/O of Thr recorded in the present study was much lower (<0.42). We speculate that Thr may be extracted in forms other than FAA (such as peptide bond AA) by the mammary under conditions of the present study. Consistent with the results of other authors, mammary uptake of Arg was two times more than milk output even in the control treatment, which suggests that there may be a requirement of Arg other than milk protein synthesis in the mammary.     

Effect of polymorphic variants of GH, Pit-1, and beta-LG genes on milk production of Holstein cows

Effect of polymorphic variants of growth hormone (GH), beta-lactoglobulin (beta-LG), and Pit-1 genes on milk yield was analyzed in a Holstein herd. Genotypes of the cows for these genes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Allele frequencies were 0.884 and 0.116 for L and V variants of GH, 0.170 and 0.830 for A and B variants of Pit-1, and 0.529 and 0.471 for A and B variants of beta-LG, respectively. GLM procedure of SAS software was used to test the effects of these genes on milk yield. Results indicated significant effects of these genes on milk yield (P < 0.05). Cows with LL genotype of GH produced more milk than cows with LVgenotype (P < 0.05). Also, for Pit-1 gene, animals with AB genotype produced more milk than BB genotype (P < 0.05). In the case of beta-LG gene, milk yield of animals with AA genotype was more than BB genotype (P < 0.01). Therefore, it might be concluded that homozygote genotypes of GH (LL) and beta-LG (AA) were superior compared to heterozygote genotypes, whereas, the heterozygote genotype of Pit-1 gene (AB) was desirable.     

The effect of concentrate supplementation on milk production and cow traffic in early and late lactation in a pasture-based automatic milking system

The objective of this experiment was to establish the effect of low-concentrate (LC) and high-concentrate (HC) supplementation in the early and late periods of lactation on milk production and cow traffic in a pasture-based automatic milking (AM) system. In total, 40 cows (10 primiparous and 30 multiparous) were randomly assigned to one of the two treatments. The experimental periods for the early and late lactation trials extended from 23 February to 12 April 2015 and 31 August to 18 October 2015, respectively (49 days in each trial period). The early lactation supplement levels were 2.3 and 4.4 kg/cow per day for LC and HC, respectively, whereas the late lactation supplement levels were 0.5 and 2.7 kg/cow per day for LC and HC, respectively. Variables measured included milking frequency, milking interval, milking outcome and milking characteristics, milk yield/visit and per day, wait time/visit and per day, return time/visit and the distribution of gate passes. As the herd was seasonal (spring) calving, the experimental periods could not run concurrently and as a result no statistical comparison between the periods was conducted. There was no significant effect of treatment in the early lactation period on any of the milk production, milking characteristics or cow traffic variables. However, treatment did significantly affect the distribution of gate passes, with the HC cows recording significantly more gate passes in the hours preceding the gate time change such as hours 7 (P<0.01), 15 (P<0.05), 20, 21 (P<0.001), and 22 (P<0.05), whereas the LC treatment recorded significantly more gate passes in the hours succeeding the gate time change, such as time points 2 (P<0.01) and 10 (P<0.05). There was a significant effect of treatment in late lactation, with HC having a greater milk yield (P<0.01), milking duration and activity/day (P<0.05), while also having a significantly shorter milking interval (P<0.05) and return time/visit (P<0.01). The distribution of gate passes were similar to the early lactation period, with HC also recording a significantly greater number of gate passes during the early morning period (P<0.01) when visitations were at their lowest. Any decision regarding the supplementing of dairy cows with concentrates needs to be examined from an economic perspective, to establish if the milk production and cow traffic benefits displayed in late lactation outweigh the cost of the concentrate; thereby ensuring that the decision to supplement is financially prudent.     

High- and low-purity glycerine supplementation to dairy cows in early lactation: effects on silage intake,milk production and metabolism

This study evaluated the effects of supplemental low- and high-purity glycerine on silage intake, milk yield and composition, plasma metabolites and body condition score (BCS) in dairy cows. A total of 42 cows of the Swedish Red Breed, housed in individual tie stalls, were fed 0.25 kg of low- or high-purity glycerine on top of concentrate, twice daily, during the first 4 weeks of lactation. One-third of the cows acted as controls, receiving no glycerine. Silage was fed for ad libitum intake and concentrate was fed at restricted level of intake, about 6 kg/day for primiparous cows and 7 kg/day for multiparous cows. Feed refusals were weighed daily. Cows were milked twice daily, milk yield was recorded on four occasions per week and milk samples were collected simultaneously. Blood samples were drawn from the coccygeal vessel once a week. Low- and high-purity glycerine had no effect on silage or total dry matter intake (P = 0.38 and P = 0.75, respectively) or on BCS (P = 0.45). Cows fed high-purity glycerine tended to have higher milk yield than control cows (P = 0.06). Milk composition tended to differ among treatments. No main effects of treatment on concentration of glycerine (P = 0.44), glucose (P = 0.78), insulin (P = 0.33), non-esterified fatty acids (P = 0.33) and β-hydroxybutyrate (P = 0.15) in plasma. These data indicate that high-purity glycerine has the potential to increase milk yield, as well as enhance the milk protein concentration and milk fat + protein yield.     

Effect of dam weight and pregnancy nutrition on average lactation performance of ewe offspring over 5 years

The foetal mammary gland is sensitive to maternal weight and nutrition during gestation, which could affect offspring milk production. It has previously been shown that ewes born to dams offered maintenance nutrition during pregnancy (day 21 to 140 of gestation) produced greater milk, lactose and CP yields in their first lactation when compared with ewes born to dams offered ad libitum nutrition. In addition, ewes born to heavier dams produced greater milk and lactose yields when compared with ewes born to lighter dams. The objective of this study was to analyse and compare the 5-year lactation performance of the previously mentioned ewes, born to heavy or light dams that were offered maintenance or ad libitum pregnancy nutrition. Ewes were milked once per week, for the first 6 weeks of their lactation, for 5 years. Using milk yield and composition data, accumulated yields were calculated over a 42-day period for each year for milk, milk fat, CP, true protein, casein and lactose using a Legendre orthogonal polynomial model. Over the 5-year period, ewes born to heavy dams produced greater average milk (P=0.04), lactose (P=0.01) and CP (P=0.04) yields than offspring born to light dams. In contrast, over the 5-year period dam nutrition during pregnancy did not affect average (P>0.05) offspring milk yields or composition, but did increase milk and lactose accumulated yield (P=0.03 and 0.01, respectively) in the first lactation. These results indicate that maternal gestational nutrition appears to only affect the first lactational performance of ewe offspring. Neither dam nutrition nor size affected grand-offspring live weight gain to, or live weight at weaning (P>0.05). Combined these data indicate that under the conditions of the present study, manipulating dam weight or nutrition in pregnancy can have some effects of offspring lactational performance, however, these effects are not large enough to alter grand-offspring growth to weaning. Therefore, such manipulations are not a viable management tool for farmers to influence lamb growth to weaning.     

Effects of wet brewers grains on milk yield,milk composition and blood components of dairy cows in hot weather

Twenty multiparous Friesian cows, 60–120 days postpartum, were allotted to two groups of ten cows each according to calving date, lactation number and daily yield, and assigned randomly to one of two diets in a crossover design experiment. The control diet was 45% maize silage (dry basis) and contained ground maize, soya bean meal and wheat bran in proportions which would ensure that the dietary dry matter contained 16.5% crude protein, 3.0 Mcal metabolizable energy kg⁻¹ DM and 14% crude fibre. The treatment diet contained wet brewers grains substituted for maize silage, soya bean meal and wheat bran to change the ruminally undegradable protein from 35% to 39% of crude protein. Ground maize was included in the same quantity as in the control diet. The diets were offered individually, in tie-stalls, as total mixed rations in two equal amounts for ad libitum intakes. The experimental period lasted from 18 June to 12 August 1994. The cows were allowed exercise in an open lot without shade. Dry matter intake, milk protein content and yield, as well as content of milk lactose and non-fat solids were not significantly affected by the diet. In contrast, wet brewers grains supplementation increased actual milk yield (24.8 v. 21.7 kg day⁻¹; P < 0.05), 4% fat-corrected milk yield (25.1 v. 21.1 kg day⁻¹; P < 0.01), milk fat content (4.08 v. 3.82%; P < 0.05), milk total solids content (12.89 v. 12.44%; P < 0.05) and milk fat yield (1.01 v. 0.83 kg day⁻¹; P < 0.05). Blood plasma concentrations of glucose, total protein, albumin, urea, triglycerides, cholesterol, phospholipids, sodium, potassium, calcium, phosphorus and magnesium were not affected by treatment.     

Supplementing sow diets with palm oil during late gestation and lactation: effects on milk production,sow hormonal profiles and growth and development of her offspring

The supplementing of sow diets with lipids during pregnancy and lactation has been shown to reduce sow condition loss and improve piglet performance. The aim of this study was to determine the effects of supplemental palm oil (PO) on sow performance, plasma metabolites and hormones, milk profiles and pre-weaning piglet development. A commercial sow ration (C) or an experimental diet supplemented with 10% extra energy in the form of PO, were provided from day 90 of gestation until weaning (24 to 28 days postpartum) in two groups of eight multiparous sows. Gestation length of PO sows increased by 1 day (P<0.05). Maternal BW changes were similar throughout the trial, but loss of backfat during lactation was reduced in PO animals (C: −3.6±0.8 mm; PO: −0.1±0.8 mm; P<0.01). Milk fat was increased by PO supplementation (C day 3: 8.0±0.3% fat; PO day 3: 9.1±0.3% fat; C day 7: 7.8±0.5% fat; PO day 7: 9.9±0.5% fat; P<0.05) and hence milk energy yield of PO sows was also elevated (P<0.05). The proportion of saturated fatty acids was greater in colostrum from PO sows (C: 29.19±0.31 g/100 g of fat; PO: 30.77±0.36 g/100 g of fat; P<0.01). Blood samples taken on 105 days of gestation, within 24 h of farrowing, day 7 of lactation and at weaning (28±3 days post-farrowing) showed there were no differences in plasma concentrations of triacylglycerol, non-esterified fatty acids, insulin or IGF-1 throughout the trial. However, circulating plasma concentrations of both glucose and leptin were elevated during lactation in PO sows (P<0.05 and P<0.005, respectively) and thyroxine was greater at weaning in PO sows (P<0.05). Piglet weight and body composition were similar at birth, as were piglet growth rates throughout the pre-weaning period. A period of 7 days after birth, C piglets contained more body fat, as indicated by their lower fat-free mass per kg (C: 66.4±0.8 arbitrary units/kg; PO: 69.7±0.8 arbitrary unit/kg; P<0.01), but by day 14 of life this situation was reversed (C: 65.8±0.6 arbitrary units/kg; PO: 63.6±0.6 arbitrary units/kg; P<0.05). Following weaning, PO sows exhibited an increased ratio of male to female offspring at their subsequent farrowing (C: 1.0±0.3; PO: 2.2±0.2; P<0.05). We conclude that supplementation of sow diets with PO during late gestation and lactation appears to increase sow milk fat content and hence energy supply to piglets. Furthermore, elevated glucose concentrations in the sow during lactation may be suggestive of impaired glucose homoeostasis.     

Effects of feeding sainfoin proanthocyanidins to lactating ewes on intake,milk production and plasma metabolites

There is increasing interest in using sainfoin (Onobrychis viciifolia) to feed sheep, but it contains proanthocyanidins (PACs), and the associated effects of PAC on sheep production are not well-known. The aim of the study was to assess the effect of the presence of PAC from sainfoin, through the inclusion of polyethylene glycol (PEG), on the intake and productive parameters of local ewes bearing one male lamb. For the experiment, 20 ewes and their newborn male lambs were placed in individual indoor cages. All ewes were fed ad libitum fresh sainfoin plus 200 g/d barley. Twice daily, half of the ewes were orally dosed with only water (Sainfoin Group; n = 10), and the other half were orally dosed with 100 g/d PEG 4000 per ewe (Sainfoin + PEG Group; n = 10). Sucking lambs were permanently housed with their dams until they reached 10–12 kg BW. The intake of sainfoin was recorded daily, and its chemical composition was analysed. Weekly, the BW, body condition score (BCS), milk yields and individual milk and blood samples were recorded. At the beginning and end of the experiment, faecal samples were collected from ewes and analysed for the anthelmintic role of PAC. The chemical composition, polyphenol content and antioxidant capacity of the diet and milk were analysed. The presence of PAC did not affect the intake, BW, BCS or milk yield of the dams (P > 0.05); however, all parameters were affected by the week of lactation (P < 0.05). Milk components were affected by the week of lactation (P < 0.001), but only the polyphenol and urea contents were reduced in the presence of PAC (P < 0.01). Similarly, the presence of PAC decreased the plasma urea concentration (P < 0.01) without effect on the rest of metabolites, polyphenols and antioxidant activity (P > 0.05). The presence of PAC had no effect on parasitism (P > 0.05). In conclusion, the presence of PAC had no relevant effects on milk production, although it affected protein metabolism, as indicated by the urea contents in milk and plasma.     

TNFα Altered Inflammatory Responses,Impaired Health and Productivity,but Did Not Affect Glucose or Lipid Metabolism in Early-Lactation Dairy Cows

Inflammation may be a major contributing factor to peripartum metabolic disorders in dairy cattle. We tested whether administering an inflammatory cytokine, recombinant bovine tumor necrosis factor-α (rbTNFα), affects milk production, metabolism, and health during this period. Thirty-three Holstein cows (9 primiparous and 24 multiparous) were randomly assigned to 1 of 3 treatments at parturition. Treatments were 0 (Control), 1.5, or 3.0 µg/kg body weight rbTNFα, which were administered once daily by subcutaneous injection for the first 7 days of lactation. Statistical contrasts were used to evaluate the treatment and dose effects of rbTNFα administration. Plasma TNFα concentrations at 16 h post-administration tended to be increased (P<0.10) by rbTNFα administration, but no dose effect (P>0.10) was detected; rbTNFα treatments increased (P<0.01) concentrations of plasma haptoglobin. Most plasma eicosanoids were not affected (P>0.10) by rbTNFα administration, but 6 out of 16 measured eicosanoids changed (P<0.05) over the first week of lactation, reflecting elevated inflammatory mediators in the days immediately following parturition. Dry matter and water intake, milk yield, and milk fat and protein yields were all decreased (P<0.05) by rbTNFα treatments by 15 to 18%. Concentrations of plasma glucose, insulin, β-hydroxybutyrate, non-esterified fatty acids, triglyceride, 3-methylhistidine, and liver triglyceride were unaffected (P>0.10) by rbTNFα treatment. Glucose turnover rate was unaffected (P = 0.18) by rbTNFα administration. The higher dose of rbTNFα tended to increase the risk of cows developing one or more health disorders (P = 0.08). Taken together, these results indicate that administration of rbTNFα daily for the first 7 days of lactation altered inflammatory responses, impaired milk production and health, but did not significantly affect liver triglyceride accumulation or nutrient metabolism in dairy cows.     

Proliferation and apoptosis in subcutaneous adipose tissue of lactating cows with different genetic merit for milk yield

The aim of this study was to investigate the adipocyte size and fate in subcutaneous fat (scAT) of cows diverging for genetic merit at mid lactation stage, when anabolic activity increases and animals are in a state of positive energy balance. Twenty mid lactation cows (180 ± 20 days in milk) grouped according to the Estimated Breeding Values (EBV) for milk yield in plus (EBVp) and minus (EBVm) variants were selected. Average of adipocytes area, proliferation and apoptotic labelling index as well as DLK-1 expression, a marker of pre-adipocytes, were immunohistochemically evaluated in scAT biopsies. In EBVp cows, the BCS was lower (P < 0.01) whereas milk yield, protein, fat yield (P < 0.001) and plasma free fatty acid concentration (P < 0.05) were higher. The scAT of EBVp cows showed a significantly (P < 0.001) higher frequency between 500 and 3000 μm² classes in comparison to EBVm cows, that showed a significantly (P < 0.01) higher apoptotic labeling index. The immunohistochemical reaction showed DLK-1 positivity in scAT of EBVp cows. Taking together, the data indicate a link between milk yield genetic merit of cows, scAT morphology and function, suggesting greater dynamics and metabolic flexibility in EBVp cows.