Plant polyphenol extract supplementation affects performance, welfare, and the Nrf2-oxidative stress response in adipose tissue of heat-stressed dairy cows.

We examined the effects of a supplement of plant polyphenols extracts of green tea, capsicum, and fenugreek, and electrolytes ([Na+, K+]; AXT, Axion ThermoPlus, CCPA, France] during summer heat load on production, welfare, and oxidative stress proteins in adipose tissue (AT) of dairy cows. A total of 42 multiparous mid-lactation cows were divided into 3 groups during summer, and were fed for 2 wk either a standard milking cow diet (CTL, n = 14) or diets supplemented with 100 g/d of AXT (100AXT, n = 14), or 150 g/d of AXT (150AXT, n = 14), while being cooled 5 times a day. Then, half of the cows from each dietary treatment were cooled (CL) or not cooled (NCL) for 2 wk, after which the cooled and uncooled groups were switched for additional 2 wk. Cows were milked 3 times a day, and milk composition was analyzed at the end of each 2-wk period. Vaginal temperature (VT) was measured for 3 consecutive days in each period. Biopsies of subcutaneous AT were taken from 10 NCL cows (5 each of CTL and 150AXT) at the end of the period and examined by liquid chromatography-tandem mass spectrometry proteomics analysis. Data were analyzed with PROC MIXED of SAS (version 9.2, SAS Institute Inc.). The model included the effects of dietary treatment, cooling regimen, period, and their interactions. Protein and mRNA abundances and proteomic data (P ≤ 0.05 and fold change [FC] ± 1.5) were analyzed by t-test. Milk yields and 4% fat-corrected milk (FCM) were higher in 100AXT than in CTL; milk components were not different. Dry matter intake (DMI) was higher in 100AXT than in CTL. The effect of cooling and the interactions of period × cooling were significant for DMI, 4% FCM, energy-corrected milk, and milk/DMI. The proportion of time that VT was >39°C was lower in 100AXT and in 150AXT than in CTL. Daily rumination time was greater in 150AXT than in CTL, and lying time was greater in 100AXT and 150AXT than in CTL. Proteomics of AT demonstrated that 150AXT had increased abundances of peroxidasin (FC = 1.6), microsomal glutathione S-transferase 2 (FC = 2.5), and heme oxygenase 1 (FC = 3.6) compared with CTL. Top enriched canonical pathways included acute phase response signaling, Nrf2-mediated oxidative stress response, and lipopolysaccharide (LPS)/IL-1-mediated inhibition of RXR function. Immunoblots of AT showed a higher abundance of the transient receptor potential vanilloid 1 and of LPS binding protein in AT of 150AXT compared with CTL. Supplementation of AXT increased DMI, milk, and 4% FCM, lowered VT, improved welfare indices, and enriched the AT with Nrf2-oxidative stress response and acute phase response proteins in heat-stressed dairy cows.

Effect of forage-to-concentrate ratio on production efficiency of low-efficient high-yielding lactating cows.

Feed is usually the costliest input in lactating cow's farms. Therefore, the developing of methods for a better adjustment of feed intake to cow's energetic needs in order to improve efficiency is desired. The aim of this study was to improve feed efficiency of low-efficient (LE) cows through a moderate increase in diet forage-to-concentrate ratio. We studied the effects of replacing 8.2% corn grains in a control low-fiber (LF) diet that contained 17.5% forage neutral detergent fiber (NDF) with 7.5% wheat straw +0.7% soybean meal for a high-fiber (HF) diet that contained 23.4% forage NDF. Based on efficiency data of individual cows from the Agricultural Research Organization's herd measured in our previous study, 15 pairs of pre-classified LE multiparous mid-lactating Israeli Holstein dairy cows were selected, each pair with similar performance, intake, and efficiency data; each member of a pair was then adapted for 2 weeks to one or the other dietary treatment. Traits examined during the 5 weeks of the experiment were DM intake (DMI), eating behavior, milk production, in vivo digestibility, and estimation of feed efficiency [energy-corrected milk (ECM)/DMI and energy balance]. Cows fed the HF diet showed slower eating rate, smaller visit and meal sizes, longer daily eating time, higher visit frequency, and longer meal duration, compared to those fed the LF diet. The DMI of cows fed the HF diet was 9.1% lower, their DM digestibility decreased from 65.7 to 62.2%, and their ECM yield was 7.0% lower than in cows fed the LF diet. Feed efficiency, measured as net energy captured/digestible energy intake, improved in the cows fed the HF vs. LF diet while feed efficiency measured as ECM/DMI remained similar. Our results thus show the potential of improving feed efficiency for milk production in LE cows by increasing the forage-to-concentrate ratio.

Seasonal heat load is more potent than the degree of body weight loss in dysregulating immune function by reducing white blood cell populations and increasing inflammation in Holstein dairy cows.

We investigated the effects of seasonal heat stress and the degree of body weight (BW) loss postpartum (PP) on immune and inflammatory markers in transition dairy cows. Blood sampled twice weekly during the transition period (3 wk prepartum to 3 wk PP) from 12 peripartum Holstein cows in summer and 12 in winter was analyzed for plasma nonesterified fatty acids, the oxidative stress marker malondialdehyde (MDA), haptoglobin, and tumor necrosis factor-α (TNF-α). Complete blood counts and white blood cell (WBC) subpopulations (CD4, CD8, CD25, WC1, and CD335) were examined weekly during the transition period. Adipose tissue biopsies were taken at 7 d PP from summer-calving cows. In cows calving during seasonal heat stress, plasma TNF-α concentrations were 4.9-fold higher prepartum and 5.1-fold higher PP, and MDA concentrations were higher prepartum and PP than in winter. Hematocrit was lower prepartum and tended to be lower PP in summer compared with winter, and after adjusting to hematocrit values fewer WBC prepartum (-17%) and PP (-22%), lower monocytes prepartum (-37%) and PP (-49%), and fewer neutrophils (-25%) PP were found in summer compared with winter-calving cows. The percentages of cytotoxic T cells (CD8) and natural killer cells (CD335) were lower, as well as prepartum gamma delta-T cells (WC1) in summer compared with winter-calving cows. Moreover, lower red blood cell counts prepartum and mean platelet volume and red blood cell distribution width prepartum and PP, as well as higher hemoglobin prepartum and PP, were found in summer than winter-calving cows. In summer, cows that lost more BW PP had higher plasma MDA and TNF-α concentrations, fewer basophil numbers prepartum, a decrease in the percentage of cells expressing the IL-2 receptor (CD25), increased ratio of T helper cells (CD4):CD8, and a tendency for increased WC1 percentages in blood prepartum, as well as a higher percentage of WC1 PP and higher abundance of TNF-α and lower lipopolysaccharide-binding protein in adipose tissue compared with cows that lost less BW PP. In conclusion, seasonal heat stress during the peripartum period was associated with lower WBC counts coupled with increased levels of subacute inflammation, indicating dysregulation of immune function, whereas the degree of BW loss had minor effects. This suggests that heat load is a more potent stressor associated with immune function than the variation in the degree of BW loss PP in high-yielding peripartum dairy cows.

The distinctive short-term response of late-pregnant prolific ewes to propylene glycol or glycerol drenching.

Pregnancy toxemia is the most frequent metabolic disorder of ewes in late pregnancy. Although propylene glycol (PG) and glycerol (GLY) are common glucogenic supplements for treating pregnancy toxemia in ewes, the relative benefit of these 2 supplements is not entirely clear. Therefore, the objectives of the present study were to determine the changes during 24 h in key blood metabolites and insulin in response to PG or GLY drenching in prolific ewes. To this end, 36 multiparous late-pregnant Afec-Assaf ewes (∼132.4 d pregnant) bearing 2 to 4 fetuses, divided into 2 blocks (18 ewes in each block), with a blood ß-hydroxybutyrate (BHB) concentration of 0.5 to 1.6 mmol/L were included. Ewes were divided into 3 groups (12 ewes each; 6 ewes in each experimental day), according to their BHB levels, expected litter size, body weight, and body condition score, and were drenched with the following: (1) control group (CTL), 55 mL of water; (2) PG, 106 mL of PG (100% PG, 448 calories); or (3) GLY, 108 mL of Koforin 80 (80% GL; 448 calories). Blood samples were taken before drenching and every hour after drenching for 24 h. Plasma concentration of glucose, BHB, nonesterified fatty acids, lactate, glycerol, and insulin were determined. Because there were no effects of treatments after 12 h in the first block, the data were analyzed for 12 h after drenching rather than 24 h. The plasma glucose concentration during the first 5 h after drenching was the highest in the GLY, BHB concentration was the lowest in the PG, and the nonesterified fatty acid levels were lower in the PG compared with the CTL ewes during the first 5 h after drenching. However, glucose concentration was higher in the PG ewes at 9, 11, and 12 h after drenching than in CTL or GLY ewes. The mean lactate concentration in plasma for 12 h was 2.5- and 1.9-fold higher in the PG compared with the CTL and GLY ewes, respectively, and except at 11 h after drenching, it was significantly higher at each time point. The insulin concentration was higher in the GLY than in both other groups at 2 to 5 h after drenching. These results suggest that during the first few hours after drenching the effect of PG was more effective in reducing the BHB concentration, whereas the GLY effect was more effective in enhancing glucose concentration. The increased concentration in lactate following PG treatment suggests that the PG contribution to gluconeogenesis is mediated through its metabolism to lactate. In contrast, the lack of an effect on lactate, and the faster increase in blood glucose in response to GLY suggest that GLY has a more advanced entry point to gluconeogenesis, which influences the immediate response in enhancing the glucose blood concentration.

Saturated fat supplemented in the form of triglycerides decreased digestibility and reduced performance of dairy cows as compared to calcium salt of fatty acids.

The two most popular rumen-protected fatty acid supplements in dairy cow rations are calcium salts of palm oil fatty acid calcium salts of palm oil fatty acid (CSFA) and prilled saturated fatty acids (SFAs). The objectives of this study were to determine the effects of supplementing SFA in the form of triglycerides (TSFA), as compared to CSFA, on yields, efficiency and diet digestibility in high-yielding dairy cows. Twenty-eight (14 cows in each group) multiparous cows were fed a basal diet supplemented (on DM basis) with either 12 g/kg TSFA (~350 g/cow per day - contained 980 g/kg fat; 882.3 g/kg SFAs) or 14 g/kg CSFA (~440 g/cow per day - contained 800 g/kg fat; 566.4 g/kg SFAs). The supplement amounts in the diet were balanced according to fat content. Rumen samples were taken for measurements of ammonia and volatile fatty acids concentrations, and fecal samples were taken for digestibility measurements. The CSFA cows produced 3% higher milk yields (47.6 v. 46.2 kg/day; P < 0.0001) and 4.7% higher 4% fat-corrected milk (FCM; 44.7 v. 42.7 kg/day; P = 0.02) than the TSFA cows. No difference in milk-fat content was observed, but milk-protein content was higher in the TSFA than CSFA cows. Yields of fat and protein were similar, but lactose yields were higher in TSFA cows. There were no differences in dry matter intake or efficiency calculations between groups. The ruminal ammonia concentrations were similar between groups, whereas acetate concentrations and acetate : propionate ratio were greater for CSFA than TSFA cows. The apparent total-tract digestibility of dry (P < 0.0007) and organic matters (P < 0.0003), fat (P < 0.0001), NDF and ADF (P = 0.02) were lower in the TSFA v. CSFA cows. In conclusion, the CSFA-supplemented cows produced 3% higher milk and 4.7% higher 4% FCM than the TSFA cows. However, TSFA supplementation did not depress milk-protein content. The apparent total-tract digestibility was lower for all dietary components in the TSFA cows, which was probably due to the effects of both degree of saturation and triglyceride form of the TSFA supplement. Considering that diets were balanced according to the fat content of the supplements, the lower yields of milk and FCM observed in the TSFA than CSFA cows were likely due to the lower digestibility of the fat and other nutrients in the TSFA cows, which might have negatively influenced the dietary energy content.

Reducing milking frequency from thrice to twice daily in early lactation improves the metabolic status of high-yielding dairy cows with only minor effects on yields.

Reducing milk production during early lactation might be of interest to improve the energy balance (EB) of high-yielding dairy cows. Therefore, the objective of this study was to determine how reducing the milking frequency (MF) of high-yielding dairy cows from thrice to twice a day during the first 30 d in milk (DIM) affects yields, intake, efficiency, metabolic status, and carryover effects. To this end, 42 multiparous cows were divided into 2 groups according to their previous lactation performance, parity, and body weight. The control cows were milked 3 times a day (3ML) and the treated cows were milked twice a day (2ML) until 30 DIM and then both groups were milked 3 times a day. Milk samples were taken twice a week from 2 or 3 consecutive milkings until 45 DIM for analysis of milk solids, and both groups were followed until 100 DIM to determine the carryover effects of MF until 30 DIM. Individual dry matter intake (DMI), milk yield, and body weight were recorded daily. Blood samples were taken 3 times weekly from 14 d prepartum until 45 DIM. Milk yield during the first 30 DIM was 8.6% higher (49.3 and 45.4 kg/d, respectively), milk fat percentage was lower (3.96 and 4.27%, respectively), and the yields of all milk solids were higher in the 3ML cows than in the 2ML cows. Dry matter intake and 4% fat-corrected milk were similar between groups. The EB during the first 30 DIM was lower in the 3ML cows than in the 2ML cows, and milk yield, but not 4% fat-corrected milk yield, per unit of DMI was higher in the 3ML cows. No differences were observed between groups from 31 to 100 DIM in milk yield (∼56.3 kg/d for both groups), milk solids yield, DMI, or milk/DMI; however, fat percentage was lower and EB was higher in the 3ML cows. Blood glucose concentrations between 0 and 30 DIM were lower and ß-hydroxybutyrate concentrations were higher in the 3ML cows than in the 2ML cows, but nonesterified fatty acids concentrations were lower, which may be attributed to the lower clearance frequency of nonesterified fatty acids from the blood stream in the 2ML cows. A lower proportion of the 3ML cows (10%) ovulated ≤15 DIM compared with the 2ML cows (40%), with no beneficial effects on preovulatory follicle characteristics. Reducing the MF from thrice to twice a day during the first 30 DIM improved EB and metabolic status, with only minor effects on production.

Dietary restriction improved feed efficiency of inefficient lactating cows.

The aim of this study was to reduce voluntary dry matter intake (DMI) to increase feeding efficiency of preclassified inefficient (INE) dairy cows through restricted feeding. We studied the effects of dietary restriction on eating behavior, milk and energy-corrected milk (ECM) production, in vivo digestibility, energy balance, and measures of feed efficiency [residual feed intake (RFI) and ECM/DMI]. Before the experiment, 12 pairs of cows were classified as INE. The 2 dietary treatments consisted of ad libitum feeding versus restricted feeding of the same total mixed ration containing 36.5% roughage. Inefficient cows fed the restricted total mixed ration had a shorter eating time and lower meal and visit frequency, but a similar rate of eating, meal size, and meal duration compared with INE cows fed ad libitum. Compared with the INE cows fed ad libitum, restricted INE cows had 12.8% lower intake, their dry matter and neutral detergent fiber digestibility remained similar, and their ECM yield was 5.3% lower. Feed efficiency, measured as RFI, ECM/DMI, and net energy retained divided by digestible energy intake, was improved in the restricted INE cows as compared with the ad libitum cows. Our results show that moderate DMI restriction has the potential to improve feed efficiency of preclassified INE cows.

Invited review: Roles of dietary n-3 fatty acids in performance, milk fat composition, and reproductive and immune systems in dairy cattle.

Mammals can synthesize all of the fatty acids (FA) necessary for proper health and functioning with the exception of FA in the n-3 (omega-3) and n-6 (omega-6) families of polyunsaturated fatty acids (PUFA), which should be supplied in the diet. The PUFA are the predominant type of lipid in dairy cattle diets; however, common feedstuffs are rich in n-6 FA, whereas the supply of n-3 FA in the intensive dairy industry is mainly limited to flaxseed and fish oils. The n-3 FA are involved in many biological systems and processes, and therefore their dietary supplementation is of special interest in dairy cattle. Furthermore, because milk, milk products, and meat are among the most important and widely used components in traditional and modern human diets, enrichment of these food products with n-3 FA is of special importance. The purpose of this review is to provide a comprehensive description of different aspects and outcomes involved in dietary n-3 FA supplementation in dairy cattle. I provide an inclusive review of the effects of n-3 FA on milk and milk solids and the FA profile in milk fat upon feeding a variety of flaxseed products or fish oil. Selective uptake of n-3 FA has been demonstrated in the ovary compartments, as well as in bull sperm and in the unborn calf through the placenta. Incorporation of these unique FA into the reproductive system influences many processes and exerts some positive effects on fertility. In addition, beneficial effects of feeding n-3 FA on the reproductive system of females and males can be achieved with supplementation of α-linolenic acid from flaxseed or from eicosapentaenoic and docosahexaenoic acids from fish oil. This work provides a broad perspective and demonstrates the importance and potential of n-3 FA dietary supplementation in dairy cattle on the animal itself, as well as its secondary effects, which are associated with human nutrition and health.

Preovulatory follicle characteristics and oocyte competence in repeat breeder dairy cows.

The varied and elusive etiology of repeat breeding (RB) in dairy cows necessitates evaluation of oocytes and follicles, which have not previously been assessed together. Accordingly, we evaluated characteristics of preovulatory follicles and the competence of oocytes in control (CTL) and RB cows. The estrous cycles of 35 cows (18 CTL and 17 RB) were synchronized using PGF2α and estrus detection. Cows with a corpus luteum were treated with PGF2α and, 14 to 15 d after a visible behavioral estrus, they were administered a second PGF2α, followed 48 h later by follicular fluid (FF) aspiration of the preovulatory follicles. Estradiol (E2)-active preovulatory follicles did not differ in diameter between the 2 groups of cows. However, FF of RB cows had higher E2 concentrations than that of CTL cows: 1,854.9 and 1,073.6 ng/mL, respectively, but similar androstenedione and progesterone concentrations. In the second part of the study, 14 consecutive ovum pick-ups (OPU) were performed in 5 CTL and 5 RB cows, at 3- to 4-d intervals. The RB and CTL cows did not differ in average numbers of follicles available per cow per session (7.1 and 7.3, respectively), oocyte recovery rates (42.2 and 44.1%, respectively), or cleavage rates (57.6 and 63.4%, respectively), but blastocyst production was markedly less in RB than in CTL cows (12.5 and 29.2%, respectively). We conclude that part of the RB cows' etiology occurs at an earlier phase of folliculogenesis, thereby impairing oocyte competence, and subsequently reducing the probability of normal fertilization, which diminish embryo vitality and development.

Consistent magnitude of postpartum body weight loss within cows across lactations and the relation to reproductive performance.

Great variation exists among cows in the magnitude of tissue mobilization during early lactation; however, it is not known whether this is an intrinsic trait. Our aims were (1) to test whether the degree of body weight (BW) loss is consistent within cows across lactations by examining daily BW records of 4 to 5 consecutive lactations and their relation to milk yield, health disorders, and reproductive performance; and (2) to examine, in an intensive study, the possible underlying physiological mechanism. Data from 416 first to fifth consecutive lactations obtained from 92 Israeli high-yielding Holstein dairy cows were analyzed. Cows were divided according to percentage of BW loss from wk 1 to 5 postpartum in their last lactation, into groups of (1) low weight loss (LWL; -3 to 6%; n = 37) and (2) high weight loss (HWL; 7 to 17%; n = 55). The average percentage of BW loss was 7.6% in the HWL group and 5.3% in the LWL group, and the pattern was consistent between groups across lactations. Milk and 4% fat-corrected milk yields during the first 30 d in milk across lactations were higher in HWL than in LWL groups, but 305-d yields were similar. The number of open days and the interval between lactations were consistent across lactations, 17 and 20 d longer, respectively, in HWL versus LWL cows. Across lactations, the conception rates from first, second, and third artificial inseminations were 9.6% higher in LWL than in HWL cows. No differences in the incidence of health disorders were observed between groups. The intensive study was conducted with 12 randomly selected peripartum cows divided into c-HWL and c-LWL groups according to the same criteria. Similar dry matter intake and efficiency calculations were observed between groups postpartum, implying that the differences may not be related to these factors. In response to a glucose-tolerance test, c-HWL cows had higher insulin secretion pre- and postpartum than c-LWL cows, suggesting the former had lower sensitivity to insulin. This is the first study demonstrating that the magnitude of BW loss postpartum within cows is consistent across lactations, and this trait is associated with reproductive performance. The degree of BW loss postpartum, regardless of genetic merit for milk production, seems to be an intrinsic trait that represents the variation in trade-off toward tissue mobilization between cows.

Future consequences of decreasing marginal production efficiency in the high-yielding dairy cow.

The objectives were to examine the gross and marginal production efficiencies in high-yielding dairy cows and the future consequences on dairy industry profitability. Data from 2 experiments were used in across-treatments analysis (n=82 mid-lactation multiparous Israeli-Holstein dairy cows). Milk yields, body weights (BW), and dry matter intakes (DMI) were recorded daily. In both experiments, cows were fed a diet containing 16.5 to 16.6% crude protein and net energy for lactation (NEL) at 1.61 Mcal/kg of dry matter (DM). The means of milk yield, BW, DMI, NEL intake, and energy required for maintenance were calculated individually over the whole study, and used to calculate gross and marginal efficiencies. Data were analyzed in 2 ways: (1) simple correlation between variables; and (2) cows were divided into 3 subgroups, designated low, moderate, and high DMI (LDMI, MDMI, and HDMI), according to actual DMI per day: ≤ 26 kg (n=27); >26 through 28.2 kg (n=28); and >28.2 kg (n=27). The phenotypic Pearson correlations among variables were analyzed, and the GLM procedure was used to test differences between subgroups. The relationships between milk and fat-corrected milk yields and the corresponding gross efficiencies were positive, whereas BW and gross production efficiency were negatively correlated. The marginal production efficiency from DM and energy consumed decreased with increasing DMI. The difference between BW gain as predicted by the National Research Council model (2001) and the present measurements increased with increasing DMI (r=0.68). The average calculated energy balances were 1.38, 2.28, and 4.20 Mcal/d (standard error of the mean=0.64) in the LDMI, MDMI, and HDMI groups, respectively. The marginal efficiency for milk yields from DMI or energy consumed was highest in LDMI, intermediate in MDMI, and lowest in HDMI. The predicted BW gains for the whole study period were 22.9, 37.9, and 75.8 kg for the LDMI, MDMI, and HDMI groups, respectively. The present study demonstrated that marginal production efficiency decreased with increasing feed intake. Because of the close association between production and intake, the principle of diminishing marginal productivity may explain why increasing milk production (and consequently increasing intake) does not always enhance profitability. To maintain high production efficiency in the future, more attention should be given to optimizing rather than maximizing feed intake, a goal that could be achieved by nutritional manipulations that would increase digestibility or by using a diet of denser nutrients that would provide all nutritional requirements from lower intake.

Behavioral and hormonal pattern of repeat breeder cows around estrus.

Repeat breeder (RB) cows were compared with normal (CTRL) ones with respect to behavioral estrus intensity, endocrine patterns and concentrations of plasma estradiol, progesterone and LH around estrus, and ovulation timing. A total of 27 and 31 cycles in 12 RB and 18 CTRL cows, respectively, were synchronized by means of the Ovsynch protocol followed by a single PG injection after 7 days. Behavioral estrus and ovulation were observed in 81.5 and 83.8% of the synchronized cycles in the RB and CTRL cows respectively. The RB and CTRL groups had similar estrus durations of 21.4 and 19.6 h respectively, but estrus was more intense in the RB, as indicated by numerically higher overall activity indexes and higher peak neck activity. The interval from PG injection to estrus onset (considered as proestrus) was 8.2 h shorter in RB than in CTRL cows, at 47.9 and 56.1 h respectively (P<0.007), but the average preovulatory follicle size was similar. The estradiol concentration at peak was numerically higher (21%) and the AUC tended to be higher in the RB cows than in the CTRL cows. LH secretion during the period from 18 to 3 h before the LH peak was also lower in RB than in CTRL cows: 2.5 and 4.6 ng/ml respectively (P<0.01). In conclusion, the behavioral estrus was more intense in the RB cows; nevertheless, short proestrus and subdued LH concentrations before the LH peak, which could impair oocyte competence and development, were first reported in RB cows.

Time required to determine performance variables and production efficiency of lactating dairy cows.

Thirty-five lactating dairy cows throughout weeks of lactation (WOL) 16 to 30 were used to determine optimal time needed for reliable measurement of performance variables, and to classify the cows into high-, medium-, and low-efficiency groups. Individual performance variables [body weight (BW), dry matter intake (DMI), and milk production] were measured daily with a computerized monitoring system. Body condition was visually scored weekly and used to calculate retained or depleted body energy as a result of fat content change (REF). Milk composition was analyzed weekly. Body weight, DMI, and total recovered energy (RE), which represents energy in milk production plus REF, were summarized weekly. Efficiency was calculated as RE/DMI and as residual feed intake (RFI; i.e., the difference between actual and expected DMI), which was calculated from multiple linear regression of DMI dependence on BW(0.75) and RE. Unexpectedly, it was found that BW did not affect DMI and RE/DMI. Changes and relative changes in phenotypic coefficient of variation and correlations among data from shortened tests ranging from 1 wk (WOL 16) to a sequence of 15-wk tests were used to determine optimal test period durations for 5 traits: BW, DMI, RE, RE/DMI, and RFI. Traits were fitted into a mixed model with repeated measures. For each week, the traits were summarized as a sequence of cumulative data, starting from WOL 16 and cumulated over periods that increased in 1-wk steps up to WOL 16 to 29. Weekly cumulations were compared with those for entire test period (WOL 16 to 30). Consistency of each cow's efficiency classification as high, medium, or low was tested by the total-agreement procedure; the kappa index P-value was used. Throughout WOL 16 to 30, the effects of increasing test period duration on between-animal coefficient of variation differed with respect to the various performance variables and RE/DMI: it tended to change with respect to BW, did not change with respect to DMI, and decreased with respect to RE and RE/DMI. In conclusion, compared with a 15-wk study, a 2-wk study can classify RFI and RE/DMI to 3 efficiency levels, with an individual correlation coefficient of 0.6. When the study was carried out over 3 wk or more, the lowest significant index of the classification was P<0.004, the lowest individual correlation coefficient was 0.65, and its lowest significance was P<0.01. The current study indicated that the insignificant effect of the BW of dairy lactating cows on their DMI should be validated in more studies.

Development of an automatic cow body condition scoring using body shape signature and Fourier descriptors.

Body condition evaluation is a common tool to assess energy reserves of dairy cows and to estimate their fatness or thinness. This study presents a computer-vision tool that automatically estimates cow's body condition score. Top-view images of 151 cows were collected on an Israeli research dairy farm using a digital still camera located at the entrance to the milking parlor. The cow's tailhead area and its contour were segmented and extracted automatically. Two types of features of the tailhead contour were extracted: (1) the angles and distances between 5 anatomical points; and (2) the cow signature, which is a 1-dimensional vector of the Euclidean distances from each point in the normalized tailhead contour to the shape center. Two methods were applied to describe the cow's signature and to reduce its dimension: (1) partial least squares regression, and (2) Fourier descriptors of the cow signature. Three prediction models were compared with manual scores of an expert. Results indicate that (1) it is possible to automatically extract and predict body condition from color images without any manual interference; and (2) Fourier descriptors of the cow's signature result in improved performance (R(2)=0.77).

Dietary α-linolenic acid from flaxseed oil improved folliculogenesis and IVF performance in dairy cows, similar to eicosapentaenoic and docosahexaenoic acids from fish oil.

The objectives of this study were to determine the differential incorporation of various omega-3 (n-3) fatty acids (FAs) supplemented to dairy cows into ovarian compartments and assess the effects on IVF. Forty-two 256-day pregnant cows were supplemented with encapsulated fats, in treatments designated as i) SFA - saturated fat at 240 and 560 g/day per cow, prepartum and post partum (PP) respectively; ii) FLX - flaxseed oil at 300 and 700 g/day per cow prepartum and PP respectively; and iii) FO - fish oil at 300 and 700 g/day per cow prepartum and PP respectively. Commencing at 60 days in lactation, ovum pickup (OPU) was performed twice weekly (20 sessions; five cows per group) and in vitro maturation and IVF were conducted. The proportion of α-linolenic acid (ALA) was greater in follicular fluid (FF), granulosa cells, and cumulus-oocyte complexes (COCs) of FLX cows than in other groups (P<0.001). The proportion of docosahexaenoic acid (DHA) was 6.7 times as great in FF of FO as in other groups (P<0.001); docosapentaenoic acid n-3 and DHA were detected in COCs of FO but not in others. The follicle number during OPU was higher in FLX and FO than in SFA (P<0.05), and the oocyte cleavage rate was higher in FLX and FO than in SFA (P<0.01). Also, the percentage of oocytes that developed to blastocysts tended to be higher in both n-3 groups than in SFA (P<0.1). In conclusion, both dietary n-3 FAs similarly improved folliculogenesis and IVF performance; therefore, ALA-rich botanical n-3 seems to be a satisfactory approach to improve oocyte quality.

Periparturient dairy cows do not exhibit hepatic insulin resistance, yet adipose-specific insulin resistance occurs in cows prone to high weight loss.

The periparturient period in dairy cows is associated with alterations in insulin action in peripheral tissues; however, the molecular mechanism underlying this process is not completely understood. The objective was to examine the response to a glucose tolerance test (GTT) and to analyze insulin signaling in liver and adipose tissues in pre- and postpartum dairy cows. Liver and adipose tissue biopsies were taken before and after GTT, at 17d prepartum and again at 3 to 5d postpartum from 8 high-yielding Israeli Holstein dairy cows. Glucose clearance rate after GTT was similar pre- and postpartum. Basal insulin concentrations and the insulin response to GTT were approximately 4-fold higher prepartum than postpartum. In accordance, phosphorylation of the hepatic insulin receptor after GTT was higher prepartum than postpartum. Across periods, a positive correlation was observed between the basal and peak plasma insulin and phosphorylated insulin receptor after GTT in the liver. Hepatic phosphorylation of protein kinase B after GTT was elevated pre- and postpartum. Conversely, in adipose tissue, phosphorylation of protein kinase B after GTT pre- and postpartum was increased only in 4 out of 8 cows that lost less body weight postpartum. Our results demonstrate that hepatic insulin signaling is regulated by plasma insulin concentrations as part of the homeorhetic adjustments toward calving, and do not support a model of hepatic insulin resistance in periparturient cows. Nevertheless, we suggest that specific insulin resistance in adipose tissue occurs pre- and postpartum only in cows prone to high weight loss. The different responses among these cows imply that genetic background may affect insulin responsiveness in adipose tissue pre- and postpartum.

Milk fat responses to butterfat infusion during conjugated linoleic acid-induced milk fat depression in lactating dairy cows.

During diet-induced milk fat depression (MFD), the short and medium-chain fatty acids (SMCFA), which are synthesized de novo in the mammary gland, are reduced to a much greater extent than the long-chain fatty acids (LCFA) that originate from the circulation. Our hypothesis was that increased availability of SMCFA might rescue conjugated linoleic acid (CLA)-induced MFD in lactating dairy cows. To test that hypothesis, 4 rumen-fistulated lactating Holstein cows (128 ± 23 d in milk) were used in a 4 × 4 Latin square design with 3-wk experimental periods. Treatments were applied during the last 2 wk of each period and included 3× daily abomasal infusion of a total of (1) 230 g/d of LCFA (blend of 59% cocoa butter, 36% olive oil, and 5% palm oil); (2) 420 g/d of butterfat (BF); (3) 230 g/d of LCFA with 27 g/d of CLA (LC-CLA), containing 10 g/d of trans-10,cis-12 CLA; and (4) 420 g/d of butterfat with 27 g/d of CLA (BF-CLA). Butterfat provided 50% of C16 (115 g/d) and similar amounts of C18 FA as found in LCFA, such that the difference between the BF and LCFA treatments was 190 g/d of SMCFA. No treatment effects were observed for DMI or milk yield. Milk fat content was reduced by 41 and 32%, whereas milk fat yield was reduced by 41 and 38% with LC-CLA and BF-CLA, respectively, compared with their respective controls. Abomasal infusion of CLA reduced de novo synthesized fatty acid (DNFA; SMCFA and 50% C16:0) concentration, whereas DNFA tended to be greater with BF infusion. An interaction was observed between SMCFA and CLA as the increased availability of SMCFA reduced stearoyl-CoA-desaturase-1 gene expression, whereas it tended to reduce lipoprotein lipase (LPL), 1-acylglycerol-3-phosphate O-acyltransferase 6 (AGPAT-6), sterol regulatory element-binding protein cleavage-activating protein (SCAP), and peroxisome proliferator-activated receptor γ (PPAR-γ) gene expression in the presence of CLA. The mRNA expression of genes involved in de novo fatty acid synthesis [acetyl-coenzyme A carboxylase α (ACACA) and fatty acid synthase (FASN)], fatty acid uptake (LPL), and triglyceride synthesis [AGPAT-6 and diacylglycerol O-acyltransferase 1 (DGAT-1)] along with protein abundance of the ACC and FASN were reduced with CLA. However, the increased availability of SMCFA had no effect on lipogenic gene expression except for LPL, whose expression was increased with BF infusion. The nutritional manipulation by increasing the intestinal availability of SMCFA was not sufficient to rescue CLA-induced MFD.

Follicular characteristics and luteal development after follicle-stimulating hormone induced multiple ovulations in heifers.

A protocol based on small doses of FSH was examined for the induction of double or triple (multiple) ovulations in cattle. Ovulation rate, follicular characteristics, and luteal responses were determined. In Exp. 1, three groups of estrous-synchronized, cyclic Holstein heifers were treated once daily, on d 3 to 6 of the cycle, with a FSH product (Folltropin-V): large FSH dose (total of 150 mg; n=18), medium FSH dose (total of 130 mg, n=12), and small FSH dose (total of 80 mg; n=7). Controls received saline (n=6). Prostaglandin F(2α) was injected on d 6, ultrasound-guided aspiration of surplus follicles (if needed) was performed on d 7, and GnRH was injected on d 8 to induce ovulation. The large FSH dose induced growth of more (2.6±0.3, P<0.05) large follicles than controls on d 8; medium and small FSH doses insufficiently stimulated growth of <2 large follicles. Ovulation rates were determined in subgroups of heifers (n=10, 13, 4, and 6, respectively). The large FSH dose induced greater rates (P<0.01) of mostly double and triple ovulations (90% multiple ovulations, 70% double ovulations), most of which (89%) were bilateral, with only 2 out of 10 heifers requiring aspiration of surplus follicles. Medium and small FSH doses induced fewer multiple ovulations (38% and 25%, respectively). Estradiol concentrations on d 8 did not differ among treatments, but the concentration per large follicle in controls was greater (P<0.05) than in FSH treatments. Mean corpus luteum (CL) volume in single-ovulation controls was greater (P<0.05) than that of multiple ovulations in the large FSH group and total CL volume and progesterone concentrations were numerically greater in multiple ovulations. In Exp. 2, the characteristics of follicles aspirated on d 7 from large FSH (n=11) and control heifers (n=10) were compared. Based on estradiol-to-progesterone ratio, 57% of the large FSH-treated follicles were classified as codominant/healthy follicles and 43% as subordinate/early atretic. Although concentrations of estradiol and androstenedione in FSH-treated codominant follicles were less (P<0.05) than in controls, estradiol-to-progesterone ratio indicated that those follicles were steroidogenically active. Finely tuned small doses of FSH administered during the first follicular wave can induce a large incidence of double/triple, mainly bilateral, ovulations in cattle, which may serve as a basis for treatment aimed at promoting twinning in beef cattle.

Transfer rate of α-linolenic acid from abomasally infused flaxseed oil into milk fat and the effects on milk fatty acid composition in dairy cows.

The objectives of the present study were to evaluate the transfer efficiency of α-linolenic acid (ALA) from the abomasum into milk fat, its interaction with milk fat content and yield, and the relationship between ALA and C16:0 in milk fat. Three rumen-fistulated multiparous Holstein cows at midlactation were used in a 3×3 Latin square design. Treatments consisted of abomasal infusion of (1) 110 mL of water/d (control), (2) 110 mL of flaxseed oil/d (low flaxseed oil, LFO), and (3) 220 mL of flaxseed oil/d (high flaxseed oil, HFO). Experimental periods were continued for 2 wk and fat supplements were infused abomasally during the last 7 d of each period. Average dry matter intake and milk yield were not affected by oil infusion. Milk fat and lactose content tended to be greater with flaxseed infusion compared with the control. Plasma ALA was 2.9- and 4.0-fold greater with LFO and HFO, respectively. The apparent transfer efficiency of ALA to milk was 44.8 and 45.7% with LFO and HFO, respectively. The C16:0 content in milk fat was decreased by 3.59 and 5.25 percentage units, whereas the ALA content was increased by 1.68 and 3.09 percentage units with LFO and HFO, respectively. Similarly, C18:2n-6 was increased by 0.95 and 1.31 percentage units with LFA and HFO, respectively, without changes in other fatty acids (FA). Total polyunsaturated FA was 4.4 and 2.7% lower in the HFO and LFO, respectively, than in the control. Furthermore, C16:0 content in the milk fat was reduced to a greater extent than the increase in ALA content, as a 1.68 and 3.09 percentage unit increase occurred in ALA compared with a 3.6 and 5.25 percentage unit decrease in C16:0 for LFO and HFO, respectively, such that a negative correlation existed between ALA and C16:0 (r=-0.72). In conclusion, abomasal infusion of flaxseed oil dramatically increased the ALA content in plasma and milk fat. Because the replacement of C16:0 with ALA and C18:2n-6 occurred without changes in other FA presumed to be synthesized de novo in the mammary gland, this suggests that the preformed C16:0 was replaced, rather than being caused, by an overall suppression of de novo FA synthesis in the mammary gland.

Performance and welfare of high-yielding dairy cows subjected to 5 or 8 cooling sessions daily under hot and humid climate.

The objectives were to determine the effects of cooling of high-yielding dairy cows under a hot and humid climate on intake, milk yield, rumination time, and welfare parameters. Forty-two multiparous Israeli Holstein dairy cows were divided into 2 treatment groups and were housed in an open barn divided into 2 pens. The groups were subjected to different cooling schedules, in a crossover design as follows: cows were exposed to 5 or 8 cooling sessions per day (designated 5CS and 8CS, respectively) in the holding area of the milking parlor. Each period lasted 4 wk, and then treatments were switched for another 4-wk period. Each cooling session lasted 45 min, comprising cycles of 30s of showering and 4.5 min of ventilation without showering. Respiration rate and rectal temperature were recorded twice per week (Monday and Thursday) at 0630 and 1600 h. Rumination and lying times were recorded automatically. Rectal temperatures were 0.16 and 1.08°C lower in 8CS than in 5CS cows in the morning and afternoon, respectively. Respiration rate was lower in 8CS than in 5CS cows in the morning (49.1 and 54.6 breaths/min, respectively), and more so in the afternoon (50.0 and 83.0 breaths/min, respectively). Dry matter intake and milk yields were 9.3 and 9.6% higher in the 8CS than in the 5CS cows (27.0 vs. 24.7 and 40.1 vs. 36.6 kg/d, respectively), with no differences in milk fat and protein contents. Daily rumination time was 7.4% longer in the 8CS than in the 5CS (440.1 and 409.6 min/d, respectively); however, rumination time per unit of dry matter or neutral detergent fiber consumed was higher in the 5CS than in the 8CS cows. Although the 8CS cows moved 3 times more to the milking area for extra cooling sessions than the 5CS ones, they spent 9.9 min/d more than the 5CS ones in lying down (484.4 and 474.5 min/d, respectively), and used more of their free time (excluding milking and feeding time) in resting than the 5CS cows: 52.0 and 43.9%, respectively. It appears that increasing the cooling frequency from 5 to 8 times per day improved their feeling of welfare, so they could spend more time lying and ruminating. In conclusion, increasing the cooling frequency of high-yielding dairy cows under hot and humid conditions from 5 to 8 times a day increased their intake and milk yield, and lowered their respiration rate and rectal temperature. Moreover, the 8CS cows spent more time resting than 5CS cows, an indication that increasing cooling frequency improved animal welfare.