Pre- and post-weaning nutrition status affects sheep mammary gland morphology and promotes differential gene expression.

Little is known about how varying the plane of nutrition before and after weaning can influence gene expression that drives mammary gland development (MGD). Therefore, the aim of this study was to investigate this paradigm in a seasonal sheep breed. Forty pre-weaning 30-day old Kurdish female lambs were fed either a low-nutrient and protein (L; 2.0 Mcal ME/kg DM; 8.70% crude protein [CP]) or high-nutrient and protein diet (H; 2.5 Mcal ME/kg DM; 14.80% CP). At d 120 (weaning), lambs were allocated into a 2 × 2 arrangement based on pre- and post-weaning diets, resulting in four groups (LL, LH, HL, HH). On d 210, mammary biopsy samples were taken for histomorphological and gene expression studies. Alveoli were larger in HH compared with all other groups (p < 0.05). Whilst estrogen receptor-alpha, progesterone receptor, growth hormone receptor and insulin-like growth factor binding protein-1 gene expression was modulated depending on pre- or post-weaning nutritional levels (p < 0.01). Overall, a consistent high plane of nutrition promoted MGD, with more a complex relationship evident between the expression of genes critical for mammary gland function and development. These findings provide scope for future tailored nutritional strategies to optimize both liveweight gain and MGD.

Short communication: effect of dietary supplementation with a mixture of fish and sunflower oils on the expression of key lipogenic and cholesterologenic genes in adipose tissues with different metabolic functions.

The present study investigated the effects of dietary fish and sunflower oils as sources of n-3, n-6 polyunsaturated fatty acids (PUFA) on the expression of key lipogenic and cholesterologenic genes in subcutaneous adipose tissue (SAT) and tail adipose tissue (TAT) of fat-tailed sheep. Twenty-six male Afshari lambs were divided into 4 groups. Three groups were fed a high concentrate basal diet plus 100 g/lamb/day oil supplement (OS; 60 g sunflower oil and 40 g fish oil) beyond a 21-day adaptation period for 10, 20, and 30 days (groups OS10, OS20, and OS30; n = 6, each) until slaughter. A control group was slaughtered at the last day of adaptation (OS0; n = 4). Expression of PPARγ, SREBP-1c, and SREBP-2 were determined in TAT and SAT. All transcription factors had lower expression in SAT than TAT. Feeding OS induced a similar pattern of SREBP-1c expression in both TAT and SAT with highest values in OS20. SREBP-2 mRNA decreased by > 50% in TAT of OS30 compared to OS0, whereas the expression of SREBP-2 mRNA did not change in SAT in the same period. PPARγ expression was not affected over time either in SAT or TAT. Plasma concentrations of cholesterol and blood urea nitrogen increased in OS20. The comparison of gene expression responses to OS in TAT vs. SAT suggest that PUFA-mediated effects on lipid metabolism differ between SAT and TAT, which may be linked to the specific role of TAT in energy and water balance under arid conditions.

The potential interaction between body condition score at calving and dietary starch content on productive and reproductive performance of early-lactating dairy cows.

Improving reproductive performance is one of the most important factors affecting the profitability of dairy herds. This study investigated the effect of feeding a high starch (HS) diet and body condition score (BCS) at calving on blood metabolites, fertility and ovarian function and milk production in Holstein dairy cows. One hundred seventy-four multiparous cows were fed common close-up and early lactation diets during the first 15 days in milk (DIM). Cows were randomly assigned to 1 of 2 experimental diets from 16 until 50 DIM (n = 87 per group); normal starch (228 g/kg diet DM; NS) or HS (270 g/kg diet DM; HS) diets. Each treatment group was further subdivided based on BCS at calving as normal BCS (BCS ⩽ 3.5; normal BCS (NBCS); n = 45) or high BCS (HBCS) (BCS ⩾ 3.75; HBCS; n = 42). A significant difference was detected for increased milk production (47.24 v. 44.55 kg/day) and decreased milk fat (33.93 v. 36.33 g/kg) in cows fed HS or NS, respectively. Plasma glucose and insulin concentrations were significantly higher in cows fed the HS compared to the NS diet. Diets significantly affected DIM at first artificial insemination (AI, 79.51 ± 3.83 v. 90.40 ± 3.83 days for cows fed HS and NS diets, respectively). High BCS groups had greater milk fat content and elevated plasma nonesterified fatty acids (NEFA), ß hydroxybutyrate (BHB) and bilirubin concentrations. In general, feeding higher starch diets to normal BCS cows during the first 50 DIM improved productive and reproductive performance of early-lactating dairy cows.

Short communication: Effects of diets containing supplemental fats on ruminal fermentation and milk odd- and branched-chain fatty acids in dairy cows.

There is a growing interest in odd- and branched-chain fatty acids (OBCFA) in milk following reports that several branched-chain fatty acids (FA) have health promoting effects, and certain milk OBCFA could serve as a biomarker to assess ruminal function. Twenty-four Holstein cows were fed 3 low-forage diets containing 30 g/kg of dry matter of prilled palm fat (PPF), sunflower oil (SO), or an equal mixture of both fats (experiment 1) or 3 diets containing 30 g/kg of dry matter of SO with a forage-to-concentrate ratio of 39:61, 44:56, or 48:52 (Experiment 2); diets were fed to investigate milk OBCFA composition and to explore the relationships between ruminal VFA and milk OBCFA using principal component analysis. Including SO in diets decreased yields of milk 13:0 anteiso, 15:0 anteiso, 15:0, 17:0, cis-9 15:1, and cis-9 17:1 compared with PPF. The molar proportion of ruminal propionate was the lowest and the yields of milk 14:0 iso and 16:0 iso were the greatest with the diet containing both fat supplements. Replacing concentrate with forages linearly increased ruminal acetate and yields of milk 13:0 iso, 14:0 iso, 15:0 iso, 16:0 iso, 17:0 iso, 13:0 anteiso, 15:0 anteiso, 15:0, 17:0, cis-9 15:1, and cis-9 17:1. The principal component analysis revealed that ruminal molar proportion of acetate related to concentrations of milk iso FA containing <17-carbon, whereas ruminal propionate related to milk 15:0, 17:0, cis-9 15:1, and cis-9 17:1, with the stronger correlations between milk OBCFA and ruminal acetate than propionate. No associations were found between ruminal molar proportion of butyrate and milk OBCFA concentrations. The results suggest that complete replacement of PPF with SO at 30 g/kg of dry matter in low-forage diets is not an effective strategy to enhance bioactive branched-chain FA in milk, rather this feeding practice lowers anteiso FA in milk; however, increasing forage proportion in diets containing SO enhances several iso and anteiso FA in milk. The milk OBCFA concentrations have stronger correlations with ruminal acetate molar proportion than with propionate or butyrate in cows fed diets containing supplemental fats.

Effects of short-term feeding of different sources of fatty acids in pre-mating diets on reproductive performance and blood metabolites of fat-tailed Iranian Afshari ewes.

The effects of dietary omega-3 and omega-6 fatty acids (FAs) in pre-mating diets on reproductive performances and metabolic status of ewes have not been well investigated. Therefore, this study investigated the effect of supplementing different source of FAs on different aspects of reproductive performance of fat-tailed Iranian Afshari ewes. Thirty-two cycling, multiparous Afshari ewes were divided into four groups and fed one of the isocaloric and isonitrogenous diets supplemented with Sunflower oil (SFO), Fish oil (FO), calcium salt of palm oil (CaPO) and/or an equal mixture of SFO + FO (SFOFO). One day after the start of the flushing, the estrous cycles of all ewes were synchronized using 12-day CIDRs. After detecting signs of estrous, all ewes were mated with rams for 2 days. The examination of ovarian follicles was done by a transrectal ultrasonography. After counting all visible follicles, they were classified into 3 classes based on their diameters: small (≤3 mm), medium (3-4 mm) and large (≥4 mm). The results showed that fat sources had no impact on dry matter intake (DMI) and body condition score (BCS) of animals (P > 0.05). Plasma glucose, total cholesterol, and albumin concentrations also were not significantly affected by supplemental fat sources (P > 0.05). Plasma insulin levels were higher at the end of the flushing (on the day of CIDR removal) and the day of mating for ewes on CaPO diet (P < 0.05). Plasma estradiol-17ß concentration was greater on the day of mating for ewes fed FO (P < 0.05). Progesterone levels in pregnant ewes fed FO were higher 30 d after mating (11.02 ng/mL; P < 0.05). Dietary treatments had no significant effect on number of small, medium and total follicles as well as the average size of small and medium follicles at the end of the flushing and the day of mating. The number of medium follicles on the day of oestrus (mating) were significantly higher for the ewes fed FO or SFO diets (P < 0.05). Likewise, the mean number and size of large follicles at the end of flushing and the day of oestrus were higher in ewes on FO diet (P < 0.05). Lambing rate and twinning rate increased (P < 0.05) in ewes fed FO or SFO, respectively. In conclusion, supplementation of n-3 PUFA rich FA especially FO in pre-mating diets showed beneficial effects on some indices of reproductive performance of Afshari ewes including lambing and twining rate due to higher number of medium sized follicles and size of the ovulatory (large) follicles at the day of oestrus and increased plasma progesterone levels in pregnant ewes.

Fat source and dietary forage-to-concentrate ratio influences milk fatty-acid composition in lactating cows.

On the basis of the potential benefits to human health there is an increased interest in producing milk containing lower-saturated fatty acid (SFA) and higher unsaturated fatty acid (FA) concentrations, including cis-9 18:1 and cis-9, trans-11-conjugated linoleic acid (CLA). Twenty-four multiparous Holstein cows were used in two experiments according to a completely randomized block design, with 21-day periods to examine the effects of incremental replacement of prilled palm fat (PALM) with sunflower oil (SFO) in high-concentrate diets containing 30 g/kg dry matter (DM) of supplemental fat (Experiment 1) or increases in the forage-to-concentrate (F : C) ratio from 39 : 61 to 48 : 52 of diets containing 30 g/kg DM of SFO (Experiment 2) on milk production, digestibility and milk FA composition. Replacing PALM with SFO had no effect on DM intake, but tended to increase organic matter digestibility, yields of milk, protein and lactose, and decreased linearly milk fat content. Substituting SFO for PALM decreased linearly milk fat 8:0 to 16:0 and cis-9 16:1, and increased linearly 18:0, cis-9 18:1, trans-18:1 (��4 to 16), 18:2 and CLA concentrations. Increases in the F : C ratio of diets containing SFO had no effect on intake, yields of milk, milk protein or milk lactose, lowered milk protein content in a quadratic manner, and increased linearly NDF digestion and milk fat secretion. Replacing concentrates with forages in diets containing SFO increased milk fat 4:0 to 10:0 concentrations in a linear or quadratic manner, decreased linearly cis-9 16:1, trans-6 to -10 18:1, 18:2n-6, trans-7, cis-9 CLA, trans-9, cis-11 CLA and trans-10, cis-12 CLA, without altering milk fat 14:0 to 16:0, trans-11 18:1, cis-9, trans-11 CLA or 18:3n-3 concentrations. In conclusion, replacing prilled palm fat on with SFO in high-concentrate diets had no adverse effects on intake or milk production, other than decreasing milk fat content, but lowered milk fat medium-chain SFA and increased trans FA and polyunsaturated FA concentrations. Increases in the proportion of forage in diets containing SFO increased milk fat synthesis, elevated short-chain SFA and lowered trans FA concentrations, without altering milk polyunsaturated FA content. Changes in fat yield on high-concentrate diets containing SFO varied between experiments and individual animals, with decreases in milk fat secretion being associated with increases in milk fat trans-10 18:1, trans-10, cis-12 CLA and trans-9, cis-11 CLA concentrations.