Seaweeds contain a myriad of nutrients and bioactives including proteins, carbohydrates and to a lesser extent lipids as well as small molecules including peptides, saponins, alkaloids and pigments. The bioactive bromoform found in the red seaweed Asparagopsis taxiformis has been identified as an agent that can reduce enteric CH4 production from livestock significantly. However, sustainable supply of this seaweed is a problem and there are some concerns over its sustainable production and potential negative environmental impacts on the ozone layer and the health impacts of bromoform. This review collates information on seaweeds and seaweed bioactives and the documented impact on CH4 emissions in vitro and in vivo as well as associated environmental, economic and health impacts.

This work examined preventive effects of a dietary and a medical intervention measure on postpartum (p.p.) ketogenesis in dairy cows overconditioned in late pregnancy. Sixty German Holstein cows were allocated 6 weeks antepartum (a.p.) to three high body condition score (BCS) groups (BCS 3.95 ± 0.08) and one low BCS group (LC, BCS 2.77 ± 0.14). Concentrate proportion in diet a.p. was higher (60% vs. 20%) and increase in proportion p.p. from 30% up to 50% decelerated (3 vs. 2 weeks) in high BCS groups. High BCS cows received a monensin controlled-release capsule (CRC) (HC/MO), a blend of essential oils (HC/EO) or formed a control group (HC). Performance parameters and energy status were evaluated in three periods [day (d) -42 until calving, one until 14 days in milk (DIM), 15 until 56 DIM]. Feed efficiency was 65% and 53% higher in HC/MO than in LC (p < 0.001) and HC groups (p = 0.002) in the second period. Milk fat content was higher in HC/EO (5.60 vs. 4.82%; p = 0.012) and milk urea higher in HC/MO (135 mg/kg) than in LC cows (107 mg/kg; p < 0.001). Increased p.p. levels of non-esterified fatty acids in serum were found in HC (p = 0.003), HC/MO (p = 0.068) and HC/EO (p = 0.002) in comparison with LC cows. Prevalence of subclinical and clinical ketosis was 54% and 46%, respectively, in HC group. Monensin decreased the prevalence to 50% and 7% respectively. Ruminal fermentation pattern showed higher proportions of propionate (23.43 mol % and 17.75 mol %, respectively; p < 0.008) and lower acetate:propionate ratio (2.66 vs. 3.76; p < 0.001) in HC/MO than HC group. Results suggest that a monensin CRC improved energy status and feed efficiency of transition dairy cows while essential oils failed to elicit any effect.

In feeding practice, conjugated linoleic acid (CLA) supplements are used to decrease milk fat excretion in early-lactation dairy cows to save energy to counteract the physiological negative energy balance. The present study was conducted to examine the effects of CLA on energy metabolism, changes in liver weight, and the weight of different adipose depots during early lactation. Primiparous lactating German Holstein cows (n=25) were divided into 5 groups and each group contained 5 animals. The experiment started 21 d prepartum and continued until 105 d in milk (DIM). Cows were slaughtered at 1, 42, and 105 DIM. The experiment was divided into a prepartum period (21 d prepartum until calving), period 1 (1 until 42 DIM), and period 2 (>42 until 105 DIM). In the prepartum period, all animals were housed together and fed the same diet with no CLA supplementation. At 1 DIM, an initial group, with no CLA supplementation, was slaughtered. The 20 remaining cows were assigned to 2 diets. One group received 100g/d of a control fat supplement (CON; n=10) and the other group 100g/d of a CLA supplement (CLA; n=10) from 1 DIM until slaughter. Five cows of each feeding group were slaughtered after 42 DIM and the remaining animals after 105 DIM. The CLA supplement contained approximately 10% each of trans-10, cis-12 CLA and cis-9, trans-11 CLA. During the slaughter process the empty body weight was recorded and the omental, mesenteric, retroperitoneal, and s.c. adipose depots, as well as the liver, were dissected and weighed. The CLA treatment decreased milk fat content in period 1 (14.1%). In period 2, milk fat content (25.4%) and yield (17.1%) were lower in the CLA group. No effect of CLA on milk yield was observed. The net energy intake, milk energy output, and the calculated energy balance remained unchanged by CLA supplementation. No effect of CLA on the weights of liver, omental, mesenteric, or s.c. adipose depots was observed when related to empty body weight. Liver weight increased with DIM, whereas the retroperitoneal adipose depot weight decreased at the same time. Compared with the initial group, the retroperitoneal adipose depot weight for control animals slaughtered after 42 DIM was decreased (47.7%); however, for the CLA group slaughtered after 42 DIM, a trend to a lower retroperitoneal adipose depot weight (34.0%) was observed. This suggests a CLA-induced deceleration of mobilization of the retroperitoneal adipose depot during the first 42 DIM.

The objective of the study was to investigate the effects of trans-10,cis-12 and cis-9,trans-11 conjugated linoleic acid (CLA) supplementation on body composition, mobilization or accretion of body fat and protein mass, as well as the energy metabolism of dairy cows during the first 105 d in milk (DIM). For this purpose, a comparative slaughter experiment was conducted with 25 primiparous German Holstein cows. The experiment started at 1 DIM with the slaughter of 5 animals of an initial group receiving no CLA supplement. The remaining animals were fed a CLA supplement (n=10) or a stearic acid-based control fat supplement (CON; n=10) from 1 DIM up to slaughter. After 42 DIM, 5 more cows from each treatment (42-CLA and 42-CON) were slaughtered. The remaining 5 cows in each treatment were slaughtered after 105 DIM (105-CLA and 105-CON). The animals of the CLA groups consumed 6.0 g/d of trans-10,cis-12 CLA and 5.7 g/d of cis-9,trans-11 CLA. During the slaughter process, the empty body mass was recorded and partitioned into 9 fractions (meat, bone, offal, hide, mammary gland, retroperitoneal fat, omental fat, mesenteric fat, and s.c. fat). The fractions were analyzed for dry matter, ether extract, crude protein, and ash to calculate the body composition of the empty body mass at the different slaughter times. The principle of the comparative slaughter technique was applied to estimate body fat or protein mobilization and accretion in the viewed periods from 1 DIM until 42 and 105 DIM. The heat production (HP) was calculated by subtracting the energy in milk and energy changes in body mass from the metabolizable energy intake. The body composition was not affected by CLA supplementation. However, the mobilization of body fat mass from 1 until 42 DIM was 24.1 kg in the 42-CON group and 14.3 kg in the 42-CLA group. This resulted in a trend to lower body mass (fat and protein) mobilization of 10.5 kg in the 42-CLA group. Energy mobilization from body mass was 21.2 MJ/d in the 42-CON and 11.5 MJ/d in the 42-CLA group. The HP was unchanged for the 42-CON and 42-CLA group with 123.0 and 116.9 MJ/d, respectively. From 1 until 105 DIM, the protein accretion was 4.3 kg and the daily energy retention in body protein was 1.0 MJ higher for CLA-supplemented cows. The HP was decreased in this period for the 105-CLA group (115.5 MJ/d) as compared with the 105-CON group (125.9 MJ/d). Overall, the trend for a decreased body mass mobilization suggested a protective effect of CLA supplementation against excessive use of body reserves within 42 DIM. Continuous CLA supplementation until 105 DIM increased protein accretion. The effects on body mass mobilization and protein accretion in combination with the decreased HP in the CLA-fed cows suggested a more efficient utilization of metabolizable energy in CLA-supplemented early lactation dairy cows.

Dairy cows are metabolically challenged during the transition period. Furthermore, the process of parturition represents an energy-consuming process. The degree of negative energy balance and recovery from calving also depends on the efficiency of mitochondrial energy generation. At this point, L-carnitine plays an important role for the transfer of fatty acids to the site of their mitochondrial utilisation. A control (n = 30) and an L-carnitine group (n = 29, 25 g rumen-protected L-carnitine per cow and day) were created and blood samples were taken from day 42 ante partum (ap) until day 110 post-partum (pp) to clarify the impact of L-carnitine supplementation on dairy cows, especially during the transition period and early puerperium. Blood and clinical parameters were recorded in high resolution from 0.5 h to 72 h pp. L-carnitine-supplemented cows had higher amounts of milk fat in early lactation and higher triacylglyceride concentrations in plasma ap, indicating increased efficiency of fat oxidation. However, neither recovery from calving nor energy balance and lipomobilisation were influenced by L-carnitine.